






































































I 


* 










































































yclopedia 

Of 


I ngineerin 



A General Reference Work on 

STEAM BOILERS AND PUMPS; STEAM, STATIONARY, LOCOMOTIVE, AND MARINE 
ENGINES; STEAM TURBINES; GAS AND OIL ENGINES; GAS-PRODUCERS; 
COMPRESSED AIR; REFRIGERATION; ELEVATORS; HEATING 
AND VENTILATION; MANAGEMENT OF DYNAMO- 
ELECTRIC machinery; power 
stations; etc. 


Editor-in- Chief 


LOUIS DERR, S. B., A. M. 

PROFESSOR OF PHYSICS, MASSACHUSETTS INSTITUTE OF TECHNOLOGY 


Assisted by 

CONSULTING ENGINEERS, TECHNICAL EXPERTS, AND DESIGNERS OF THE 

HIGHEST PROFESSIONAL STANDING 


Illustrated with over Two 'Thousand Engravings 


SEVEN VOLUMES 


AMERICAN TECHNICAL SOCIETY 
CHICAGO 

1918 


Copyright, 1902, 1903, 1904, 1906, 1S07, 1909, 1912, 1915, 1918 


BY 

AMERICAN TECHNICAL SOCIETY 


Copyrighted in Great Britain 
. All Rights Reserved 



MAY -6 1918 '' 


©Cl. A 4 992 9 9 


'Vvn \ 





Editor-in- Chief 

LOUIS DERR, S. B., A. M. 

Professor of Physics, Massachusetts Institute of Technology 


Authors and Collaborators 


LIONEL S. MARKS, S. B., M. M. E. 

Professor of Mechanical Engineering, in Harvard University and Massachusetts Insti¬ 
tute of Technology 

American Society of Mechanical Engineers 

V 


LLEWELLYN V. LUDY, M. E. 

Professor of Experimental Engineering, Purdue University 
American Society of Mechanical Engineers 

V» 


LUCIUS I. WIGHTMAN, E. E. 

Consulting Engineer and Counsellor in Technical Advertising, New York City 

FRANCIS B. CROCKER, E. M., Ph. D. 

Professor of Electrical Engineering, Columbia University, New York 
Past President, American Institute of Electrical Engineers 


GEORGE C. SHAAD, E. E. 

Professor of Electrical Engineering, University of Kansas 


WALTER S. LELAND, S. B. 

Representing Erie City Iron Works, San Francisco, California 

Formerly Assistant Professor of Naval Architecture, Massachusetts Institute of 
Technology 

American Society of Naval Architects and Marine Engineers 



Authors and Collaborators—Continued 


ARTHUR L. RICE, M. M. E. 

Editor, Power Plant Engineering 

Treasurer, Technical Publishing Company, Chicago 


CHARLES L. HUBBARD, S. B., M. E. 

Consulting Engineer on Heating, Ventilating, Lighting, and Power 


>• 

ROBERT H. KUSS, M. E. 

Consulting Mechanical Engineer 
International Railway Fuel Association 
American Society Mechanical Engineers 




H.S. McDEWELL, S. B., M. M. E. 

Instructor in Mechanical Engineering, University of Illinois 

Formerly Gas Engine Erection Engineer, Allis-Chalmers Manufacturing Company, 
Milwaukee, Wisconsin 
American Society of Mechanical Engineers 




GLENN M. HOBBS, Ph. D. 

Secretary and Educational Director, American School of Correspondence 
Formerly Instructor in Physics, University of Chicago 
American Physical Society 


V 

LOUIS DERR, S. B., A. M. 

Professor of Physics, Massachusetts Institute of Technology 


JOHN H. JALLINGS 

Mechanical Engineer and Elevator Expert 
With Kaestner & Hecht Company, Chicago 
For Twenty Years Superintendent and Chief Constructor for J. W. Reedy Elevator 
Company 





Authors and Collaborators—Continued 


MILTON W. ARROWOOD 

Graduate, United States Naval Academy 
Refrigerating and Mechanical Engineer 
Consulting Engineer 




HENRY L. NACHMAN 

Associate Professor of Kinematics and Machine Design, Armour Institute of Technology 




C. C. ADAMS, B. S. 

Switchboard Engineer with General Electric Company 


. V* 


CHESTER A. GAUSS, E. E. 

Formerly Associate Editor, Electrical Review and Western Electrician 




ALEXANDER D. BAILEY 

Chief Engineer, Fisk Street and Quarry Street Stations, Commonwealth Edison 
Company, Chicago 


V* 


WILLIAM S. NEWELL, S. B. 

With Bath Iron Works 

Formerly Instructor, Massachusetts Institute of Technology 


V* 


CARL S. DOW, S. B. 

With Walter B. Snow, Publicity Engineer, Boston 
American Society of Mechanical Engineers 


V* 


JESSIE M. SHEPHERD, A. B. 

Head, Publication Department, American Technical Society 



Authorities Consulted 


T HE editors have freely consulted the standard technical literature of 
Europe and America in the preparation of these volumes. They 
desire to express' their indebtedness particularly to the following 
eminent authorities, whose well-known treatises should be in the library of 
every engineer. 

Grateful acknowledgment is made here also for the invaluable co-opera¬ 
tion of the foremost engineering firms in making these volumes thoroughly 
representative of the best and latest practice in the design and construction 
of steam and electrical machines; also for the valuable drawings and data, 
suggestions, criticisms, and other courtesies. 


JAMES AMBROSE MOYER, S. B., A. M. 

Member of the American Society of Mechanical Engineers; American Institute of Elec¬ 
trical Engineers, etc.; Engineer, Westinghouse, Church, Kerr and Company 
Author of “The Steam Turbine,*’ etc. 

E. G. CONSTANTINE 

Member of the Institution of Mechanical Engineers; Associate Member of the Institu¬ 
tion of Civil Engineers 
Author of “Marine Engineers” 

'*• 

C. W. MacCORD, A. M. • 

Professor of Mechanical Drawing, Stevens Institute of Technology 
Author of “Movement of Slide Valves by Eccentrics” 

V* 

CECIL H. PEABODY, S. B. 

Professor of Marine Engineering and Naval Architecture, Massachusetts Institute of 
Technology 

Author of “Thermodynamics of the Steam Engine,” “Tables of the Properties of 
Saturated Steam,” “Valve Gears to Steam Engines,” etc. 

FRANCIS BACON CROCKER, M. E., Ph. D. 

Professor of Electrical Engineering, Columbia University; Past President, American 
Institute of Electrical Engineers 

Author of “Electric Lighting,” “Practical Management of Dynamos and Motors” 

V* 

SAMUEL S. WYER 

Mechanical Engineer; American Society of Mechanical Engineers 

Author of “Treatise on Producer Gas and Gas-Producers,” “Catechism on Producer Gas” 

E. W. ROBERTS, M. E. 

Member, American Society of Mechanical Engineers 

Author of “Gas-Engine Handbook,” “Gas Engines and Their Troubles,” “The Automo¬ 
bile Pocket-Book,” etc. 




Authorities Consulted—Continued 


GARDNER D. HISCOX, M. E. 

Author of “Compressed Air,” “Gas, Gasoline, and Oil Engines,” “Mechanical Move¬ 
ments,” “Horseless Vehicles, Automobiles, and Motorcycles,” “Hydraulic Engineer¬ 
ing,” “Modern Steam Engineering,” etc. 

V* 

EDWARD F. MILLER 

Professor of Steam Engineering, Massachusetts Institute of Technology 

Author of “Steam Boilers” 

V* 

ROBERT M. NEILSON 

Associate Member, Institution of Mechanical Engineers; Member of Cleveland Institu¬ 
tion of Engineers; Chief of the Technical Department of Richardsons, Westgarth, 
and Company, Ltd. 

Author of “The Steam Turbine” 

ROBERT WILSON 

Author of “Treatise on Steam Boilers,” "Boiler and Factory Chimneys,” etc. 

CHARLES PROTEUS STEINMETZ 

Consulting Engineer, with the General Electric Company; Professor of Electrical Engi¬ 
neering, Union College 

Author of “The Theory and Calculation of Alternating-Current Phenomena,” “Theo¬ 
retical Elements of Electrical Engineering,” etc. 

JAMES J. LAWLER 

Author of “Modern Plumbing, Steam and Hot-Water Heating” 

V* 

WILLIAM F. DURAND, Ph. D. 

Professor of Marine Engineering, Cornell University 

Author of “Resistance and Propulsion of Ships,” “Practical Marine Engineering” 

HORATIO A. FOSTER 

Member, American Institute of Electrical Engineers; American Society of Mechanical 
Engineers, Consulting Engineer 

Author of “Electrical Engineer’s Pocket-Book” 

ROBERT GRIMSHAW, M. E. 

Author of “Steam Engine Catechism,” “Boiler Catechism,” “Locomotive Catechism.” 
“Engine Runners’ Catechism,” “Shop Kinks,” etc. 


SCHUYLER S. WHEELER, D. Sc. 


Electrical Expert of the Board of Electrical Control, New York City; Member American 
Societies of Civil and Mechanical Engineers 
Author of “Practical Management of Dynamos and Motors” 



Authorities Consulted—Continued 


J. A. EWING, C. B., LL. D., F. R. S. 

Member, Institute of Civil Engineers; formerly Professor of Mechanism and Applied 
Mechanics in the University of Cambridge; Director of Naval Education 
Author of “The Mechanical Production of Cold,” “The Steam Engine and Other Heat 
Engines” 

V* 

LESTER G. FRENCH, S. B. 

Mechanical Engineer 
Author of “SteamiTurbines” 

ROLLA C. CARPENTER, M. S., C. E., M. M. E. 

Professor of Experimental Engineering, Cornell University; Member, American Society 
of Heating and Ventilating Engineers; Member, American Society of Mechanical 
Engineers 

Author of “Heating and Ventilating Buildings” 


J. E. SIEBEL 

Director, Zymotechnic Institute, Chicago 
Author of “Compend of Mechanical Refrigeration” 


WILLIAM KENT, M. E. 

Consulting Engineer; Member, American Society of Mechanical Engineers, etc. 
Author of “Strength of Materials,” “Mechanical Engineer’s Pocket-Book,” etc. 


WILLIAM M. BARR 

Member, American Society of Mechanical Engineers 
Author of “Boilers and Furnaces,” “Pumping Machinery,” “Chimneys of Brick and 
Metal,” etc. 

V* 

WILLIAM RIPPER 

Professor of Mechanical Engineering in the Sheffield Technical School; Member, The 
Institute of Mechanical Engineers 

Author of “Machine Drawing and Design,” “Practical Chemistry,” “Steam,” etc. 


J. FISHER-HINNEN 

Late Chief of the Drawing Department at the Oerlikon Works 
Author of “Continuous Current Dynamos” 


SYLVANUS P. THOMPSON, D. Sc., B. A., F. R. S., F. R. A. S. 

Late Principal and Professor of Physics in the City and Guilds of London Technical 
College 

Author of “Electricity and Magnetism,” “Dynamo-Electric Machinery,” etc. 


ROBERT H. THURSTON, C. E., Ph. B., A. M., LL. D. 

Director of Sibley College, Cornell University 

Author of “Manual of the Steam Engine,” “Manual of Steam Boilers,” “History of the 
Steam Engine,” etc. 







Authorities Consulted—Continued 


JOSEPH G. BRANCH, B. S., M. E. 

Chief of the Department of Inspection, Boilers and Elevators; Member of the Board of 
Examining Engineers for the City of St. Louis 
Author of “Stationary Engineering.” “Heat and Light from Municipal and Other 
Waste,” etc. 

JOSHUA ROSE, M. E. 

Author of “Mechanical Drawing Self Taught,” “Modern Steam Engineering,” “Steam 
Boilers,” “The Slide Valve.” “Pattern Maker’s Assistant.” “Complete Machinist.” 
etc. 

CHARLES H. INNES, M. A. 

Lecturer on Engineering at Rutherford College 

Author of “Air Compressors and Blowing Engines.” “Problems in Machine Design,” 
“Centrifugal Pumps, Turbines, and Water Motors,” etc. 

V* 

GEORGE C. V. HOLMES 

Whitworth Scholar; Secretary of the Institute of Naval Architects, etc. 

Author of “The Steam Engine” 

V* 

FREDERIC REMSEN HUTTON, E. M., Ph. D. 

Emeritus Professor of Mechanical Engineering in Columbia University; Past Secretary 
and President of American Society of Mechanical Engineers 
Author of “The Gas Engine,” “Mechanical Engineering of Power Plants,” etc. 

MAURICE A. OUDIN, M. S. 

Member of American Institute of Electrical Engineers 
Author of “Standard Polyphase Apparatus and Systems” 

WILLIAM JOHN MACQUORN RANKINE, LL. D., F. R. S. S. 

Civil Engineer; Late Regius Professor of Civil Engineering in University of Glasgow 
Author of “Applied Mechanics,” “The Steam Engine,” “Civil Engineering,” “Useful 
Rules and Tables,” “Machinery and Mill Work,” “A Mechanical Textbook” 

DUGALD C. JACKSON, C. 

Head of Department of Electrical Engineering, Massachusetts Institute of Technology 
Member of American Institute o Electrical Engineers 

Author of “A Textbook on Electro-Magnetism and the Construction of Dynamos,” 
“Alternating Currents and Alternating-Current Machinery” 

A. E. SEATON 

Author of “A Manual of Marine Engineering” 

WILLIAM C. UNWIN, F. R. S., M. Inst. C. E. 

Professor of Civil and Mechanical Engineering, Central Technical College, City and 
Guilds of London Institute, etc. 

Author of “Machine Design,” “The Development and Transmission of Power,” etc. 




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Foreword 


T HE “prime mover”, whether it be a massive, majestic 
Corliss, a rapidly rotating steam turbine, or an iron 
“greyhound” drawing the Limited, is a work of 
mechanical art which commands the admiration of everyone. 
And yet, the complicated fnechanisms are so efficiently designed 
and everything works so noiselessly, that we lose sight of the 
wonderful theoretical and mechanical development which was 
necessary to bring these machines to their present state of 
perfection. Notwithstanding the genius of Watt, which was so 
great that his basic conception of the steam engine and many 
of his inventions in connection with it exist today practically as 
he gave them to the world over a hundred years ago, yet the 
mechanics of his time could not build engine cylinders nearer 
true than three-eighths of an inch — the error in the modern 
engine cylinders must not be greater than two-thousandths 
of an inch. 

C, But the developments did not stop with Watt. The little 
refinements brought about by the careful study of the theory 
of the heat engine; the reduction in heat losses; the use of 
superheated steam; the idea of compound expansion; the devel¬ 
opment of the Stephenson and Walschaert valve gears —all 
have contributed toward making the steam engine almost 
mechanically perfect and as efficient as is inherently possible. 
C, The development of the steam turbine within recent years 
has opened up a new field of engineering, and the adoption of 
this form of prime mover in so many stationary plants like the 
immense Fisk Station of the Commonwealth Edison Company, 
as well as its use on the gigantic ocean liners like the Lusitania, 
makes this angle of steam engineering of especial interest. 





€L Adding to this the wonderful advance in the gas engine 
field — not only in the automobile type where requirements of 
lightness, speed, and reliability under trying conditions have 
developed a most perfect mechanism, but in the stationary type 
which has so many fields of application in competition with 
its steam-driven brother as well as in fields where the latter 
can not be of service — you have a brief survey of the almost 
unprecedented development in this most fascinating branch of 
Engineering. 

€1 This story has been developed in these volumes from the 
historical standpoint and along sound theoretical and prac¬ 
tical lines. It is absorbingly interesting and instructive to the 
stationary engineer and also to all who wish to follow modern 
engineering development. The formulas of higher mathematics 
have been avoided as far as possible, and every care has been 
exercised to elucidate the text by abundant and appropriate 
illustrations. 

C. The Cyclopedia has been compiled with the idea of making it 
a work thoroughly technical, yet easily comprehendible by the 
man who has but little time in which to acquaint himself with 
the fundamental branches of practical engineering. If, there¬ 
fore, it should benefit any of the large number of workers who 
need, yet lack, technical training, the publishers will feel that 
its mission has been accomplished. 

<L Grateful acknowledgment is due the corps of authors and 
collaborators — engineers and designers of wide practical expe¬ 
rience, and teachers of well-recognized ability — without whose 
co-operation this work would have been impossible. 


Table of Contents 


VOLUME VII 

Heating and Ventilation . . . By C. L. Hubbardt Page* 11 

Systems of Warming—Hot-Air Furnaces—Direct and Indirect Steam and Hot- 
Water Heating—Radiators—Exhaust Steam Heating—Ventilation—Heat Losses 
—Direct- and Indirect-Draft Furnaces—Furnace Details—Smoke-Pipes—Flues 
—Cold-Air Box—Warm-Air Pipes—Registers—Sectional, Tubular, and Water- 
Tube Boilers—Circulation Coils—Systems of Piping—Air-Valves—Blow-Off Tank 
—Expansion Tank—Back-Pressure Valve—Exhaust Head—Return Pumps and 
Traps — Damper Regulators—Vacuum Systems —Fans and Blowers — Factory 
Heating—Electric Heating—Automatic Regulators—Air-Filters and Washers— 
Heating and Ventilating Schools, Churches, etc. 


Management of Dynamo-Electric Machinery .... 

. . . . . By F. B. Crocker and C. C. Adams Page 225 

Selection of Machine—Erection: Foundations, Mechanical Connections, Assem¬ 
bling—Typical Wiring Connections: Generators, Commutating Pole Generators, 
Synchronous Converters, Three Wire System, Motors, A. C. Generators, A. C. 

Motors, Induction Motors, Synchronous Motors—Rules for Operation—Inspection 
and Testing: Wiring and Protective Apparatus, Electrical Resistance, Voltage, 
Current, Speed—Localization and Remedy of Troubles: General Plan, Sparking 
at Commutator, Heating of Commutator and Brushes, Heating of Armature, 
Heating of Field Magnets, Heating of Bearings, Noisy Operation, Speed Not 
Right, Motor Stops or Fails to Start, Dynamo Fails to Generate, Voltage Not 
Right 

Power Stations. By George C. Shaad Page 367 

Introduction—Location of Station—Selection of Generating and Transmission 
Systems—Factors in Design—Steam Plant—Boilers—Steam Piping Feed Water 
—Boiler Setting—Draft—Steam Engines—Steam Turbines—Hydraulic Plants— 

Water Turbines (Reaction and Impulse Types)—Pelton Wheel—Gas Plant 
Electric Plant—Generators—Transformers—Storage Batteries—Switchboards 
Switches — Measuring Instruments — Rheostats — Circuit-Breakers Safety 
Devices— Lightning Arresters — Substations — Motor-Generator Sets Rotary 
Converters —Synchronous Converters— Buildings Foundations Station 
Arrangement—Station Records—Office Management—Charging for Power 

Bibliography.. Page 453 

Review Questions . *.Page 465 

Index .. Page 471 


* For page numbers, see foot of pages. 

-j- F 0 r professional standing of authors, see list of Authors and Collaborators at 
front of volume. 







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HEATING AND VENTILATION 

PART I 


SYSTEMS OF WARMING 

Any system of warming must include, first, the combustion 
of fuel, which may take place in a fireplace, stove, or furnace, or a 
steam, or hot-water boiler; second, a system of transmission, by means 
of which the heat may be carried, with as little loss as possible, to the 
place where it is to be used for warming; and third, a system of dif¬ 
fusion, which will convey the heat to the air in a room, and to its 
walls, floors, etc., in the most economical way. 

Stoves. The simplest and cheapest form of heating is the stove. 
The heat is diffused by radiation and convection directly to the objects 
and air in the room, and no special system of transmission is required. 
The stove is used largely in the country, and is especially adapted 
to the warming of small dwelling-houses and isolated rooms. 

Furnaces. Next in cost of installation and in simplicity of 
operation, is the hot-air furnace. In this method, the air is drawn 
over heated surfaces and then transmitted through pipes, while at 
a high temperature, to the rooms where heat is required. Furnaces 
are used largely for warming dwelling-houses, also churches, halls, 
and schoolhouses of small size. They are more costly than stoves, 
but have certain advantages over that form of heating. They require 
less care, as several rooms may be warmed from a single furnace; 
and, being placed in the basement, more space is available in the 
rooms above, and the dirt and litter connected with the care of a stove 
are largely done away with. They require less care, as only one fire 
is necessary to warm all the rooms in a house of ordinary size. One 
great advantage in the furnace method of warming comes from the 
constant supply of fresh air which is required to bring the heat into 
the rooms. While this is greatly to be desired from a sanitary stand¬ 
point, it calls for the consumption of a larger amount of fuel than 
would otherwise be necessary. This is true because heat is required 
to warm the fresh air from out of doors up to the temperature of the 


11 



2 


HEATING AND VENTILATION 


rooms, in addition to replacing the heat lost by leakage and conduction 
through walls and windows. 

A more even temperature may be maintained with a furnace 
than by the use of stoves, owing to the greater depth and size of the 
fire, which allows it to be more easily controlled. 

When a building is placed in an exposed location, there is often 
difficulty in warming rooms on the north and west sides, or on that 
side toward the prevailing winds. This may be overcome to some ex¬ 
tent by a proper location of the furnace and by the use of extra large 
pipes for conveying the hot air to those rooms requiring special at¬ 
tention. 

Direct Steam. Direct steam, so called, is widely used in all 
classes of buildings, both by itself and in combination with other 
systems. The first cost of installation is greater than for a furnace; 
but the amount of fuel required is less, as no outside air supply is 
necessary. If used for warming hospitals, schoolhouses, or other 
buildings where a generous supply of fresh air is desired, this method 
must be supplemented by some form of ventilating system. 

One of the principal advantages of direct steam is the ability 
to heat all rooms alike, regardless of their location or of the action 
of winds. 

When compared with hot-water heating, it has still anothei 
desirable feature—which is its freedom from damage by the freezing 
of water in the radiators when closed, which is likely to happen in 
unused rooms during very cold weather in the case of the former 
system. 

On the other hand, the sizes of the radiators must be proportioned 
for warming the rooms in the coldest weather, and unfortunately 
there is no satisfactory method of regulating the amount of heat in 
mild weather, except by shutting off or turning on steam in the radia- 
ators at more or less frequent intervals as may be required, unless one 
of the expensive systems of automatic control is employed. In large 
rooms, a certain amount of regulation can be secured by dividing 
the radiation into two or more parts, so that different combinations 
may be used under varying conditions of outside temperature. If 
two radiators are used, their surface should be proportioned, when 
convenient, in the ratio of 1 to 2, in which case one-third, two-thirds, 
or the whole power of the radiation can be used as desired. 


12 




HEATING AND VENTILATION 


3 


Indirect Steam. This system of heating combines some of the 
advantages of both the furnace and direct steam, but is more costly 
to install than either of these. The amount of fuel required is about 
the same as for furnace heating, because in each case the cool fresh 
air must be warmed up to the temperature of the room, before it can 
become a medium for conveying heat to offset that lost by leakage 
and conduction through walls and windows. 

A system for indirect steam may be so designed that it will supply 
a greater quantity of fresh air than the ordinary form of furnace, in 
which case the cost of fuel will of course be increased in proportion to 
the volume of air supplied. Instead of placing the radiators in the 
rooms, a special form of heater is supported near the basement ceiling 
and encased in either galvanized iron or brick. A cold-air supply 
duct is connected with the space below the heater, and warm air pipes 
are taken from the top and connected with registers in the rooms to 
be heated the same as in the case of furnace heating. 

A separate stack or heater may be provided for each register if 
the rooms are large; but, if small and so located that they may be 
reached by short runs of horizontal pipe, a single heater may serve 
for two or more rooms. 

The advantage of indirect steam over furnace heating comes from 
the fact that the stacks may be placed at or near the bases of the flues 
leading to the different rooms, thus doing away with long, horizontal 
runs of pipe, and counteracting to a considerable extent the effect of 
wind pressure upon exposed rooms. Indirect and direct heating are 
often combined to advantage by using the former for the more import¬ 
ant rooms, where ventilation is desired, and the latter for rooms more 
remote or where heat only is required. 

Another advantage is the large ratio between the radiating sur¬ 
face and grate-area, as compared with a furnace; this results in a large 
volume of air being warmed to a moderate temperature instead of a 
smaller quantity being heated to a much higher temperature, thus 
giving a more agreeable quality to the air and rendering it less dry 

Indirect steam is adapted to all the buildings mentioned in con¬ 
nection with furnace heating, and may be used to much better advan¬ 
tage in those of large size. This applies especially to cases where 
more than 3ne furnace is necessary; for, with steam heat, a single 
boiler, or a battery of boilers, may be made to supply heat for a build- 


13 


4 


HEATING AND VENTILATION 


ing of any size, or for a group of several buildings, if desired, and is 
much easier to care for than several furnaces widely scattered. 

Direct-Indirect Radiators. These radiators are placed in the 
room the same as the ordinary direct type. The construction is such 
that when the sections are in place, small flues are formed between 
them; and air, being admitted through an opening in the outside wall, 
passes upward through them and becomes heated before entering the 
room. A switch damper is placed in the casing at the base of the 
radiator, so that air may be taken from the room itself instead of 
from out of doors, if so desired. Radiators of this kind are not used 
to any great extent, as there is likely to b$ more or less leakage of cold 
air into the room around the base. If ventilation is required, it is 
better to use the regular form of indirect heater with flue and register, 
if possible. It is sometimes desirable to partially ventilate an isolated 
room where it would be impossible to run a flue, and in cases of this 
kind the direct-indirect form is often useful. 

Direct Hot Water. Hot water is especially adapted to the warm¬ 
ing of dwellings and greenhouses, owing to the ease with which the 
temperature can be regulated. When steam is used, the radiators are 
always at practically the same temperature, while with hot water the 
temperature can be varied at will. A system -for hot-water heating 
costs more to install than one for steam, as the radiators must be larger 
and the pipes more carefully run. On the other hand, the cost of 
operating is somewhat less, because the water need be carried only at 
a temperature sufficiently high to warm the rooms properly in mild 
weather, while with steam the building is likely to become overheated, 
and more or less heat wasted through open doors and windows. 

A comparison of the relative costs of installing and operating hot¬ 
air, steam, and hot-water systems, is given in Table I. 


TABLE I 

Relative Cost of Heating Systems 



Hot Air 

Steam 

Hot Water 

Relative cost of apparatus 

Relative cost, adding repairs and fuel 

9 

13 

15 

for five years 

Relative cost, adding repairs and fuel for 

to 

ton 

29 J 

27 

fifteen years 

81 

63 

52£ 


14 











HEATING AND VENTILATION 


5 


One disadvantage in the use of hot water is the danger from 
freezing when radiators are shut off in unused rooms. This makes 
it necessary in very cold weather to have all parts of the system turned 
on sufficiently to produce a circulation, even if very slow. This is 
sometimes accomplished by drilling a very small hole (about J inch) 
in the valve-seat, to that when closed there will still be a very slow 
circulation through the radiator, thus preventing the temperature of 
the water from reaching the freezing point. 

Indirect Hot Water. This is used under the same conditions as 
indirect steam, but more especially in the case of dwellings and hospi¬ 
tals. When applied to other and larger buildings, it is customary to 
force the water through the mains by means of a pump. Larger 
heating stacks and supply pipes are required than for steam; but the 
arrangement and size of air-flues and registers are practically the 
same, although they are sometimes made slightly larger in special cases. 

Exhaust Steam. Exhaust steam is used for heating in connection 
with power plants, as in shops and factories, or in office buildings 
which have their own lighting plants. There are two methods of 
using exhaust steam for heating purposes. One is to carry a back 
pressure of 2 to 5 pounds on the engines, depending upon the length 
and size of the pipe mains; and the other is to use some form of vacuum 
system attached to the returns or air-valves, which tends to reduce 
the back pressure rather than to increase it. 

Where the first method is used and a backpressure carried, either 
the boiler pressure or the cut-off of the engines must be increased, to 
keep the mean effective pressure the same and not reduce the horse¬ 
power delivered. In general it is more economical to utilize the ex¬ 
haust steam for heating. There are instances, however, where the 
relation between the quantities of steam required for heating and for 
power are such—especially if the engines are run condensing—that 
it is better to throw the exhaust away and heat with live steam. 
Where the vacuum method is used, these difficulties are avoided; and 
for this reason that method is coming into quite common use. 
If the condensation from the exhaust steam is returned to the 
boilers, the oil must first be removed; this is usually accomplished by 
passing the steam through some form of grease extractor as it leaves 
the engine. The water of condensation is often passed through a 
separating tank in addition to this, before it is deli re red to the return 


15 




6 


HEATING AND VENTILATION 


pumps. It is better, however, to remove a portion of the oil before 
the steam enters the heating system; otherwise a coating will be formed 
upon the inner surfaces of the radiators, which will reduce their 
efficiency to some extent. 

Forced Blast. This method of heating, in different forms, is 
used for the warming of factories, schools, churches, theaters, halls— 
in fact, any large building where good ventilation is desired. The 
air for warming is drawn or forced through a heater of special design, 
and discharged by a fan or blower into ducts which lead to registers 
placed in the rooms to be warmed. The heater is usually made up in 
sections, so that steam may be admitted to or shut off from any section 
independently of the others, and the temperature of the air regulated 
in this manner. Sometimes a by-pass damper is attached, so that 
part of the air will pass through the heater and part around or over it; 
in this way the proportions of cold and heated air may be so adjusted 
as to give the desired temperature to the air entering the rooms. These 
forms of regulation are common where a blower is used for warming 
a single room, as in the case of a church or hall; but where several 
rooms are warmed, as in a schoolhouse. it is customary to use the 
main or primary heater at the blower for warming the air to a given 
temperature (somewhat below that which is actually required), and 
to supplement this by placing secondary coils or heaters at the bottoms 
of the flues leading to the different rooms. By means of this arrange¬ 
ment, the temperature of each room can be regulated independently 
of the others. The so-called double-duct system is sometimes employed. 
In this case, two ducts are carried to each register, one supplying hot 
air and the other cold or tempered air; and a damper for mixing these 
in the right proportions is placed in the flue, below the register. 

Electric Heating. Unless electricity can be produced at a very 
low cost, it is not practicable for heating residences or large buildings. 
The electric heater, however, has quite a wide field of application ifc 
heating small offices, bathrooms, electric cars, etc. It is a convenient 
method of warming isolated rooms on cold mornings, in late spring and 
early fall, when the regular heating apparatus of the building is not in 
operation. It has the advantage of being instantly available, and the 
amount of heat can be regulated at will. Electric heaters are clean 
do not vitiate the air, and are easily moved from place to place. 


16 




HEATING AND VENTILATION 


7 


PRINCIPLES OF VENTILATION 

Closely connected with the subject of heating is the problem of 
maintaining air of a certain standard of purity in the various buildings 
occupied. 

The introduction of pure air can be done properly only in con¬ 
nection with some system of heating; and no system of heating is 
complete without a supply of pure air, depending in amount upon the 
kind of building and the purpose for which it is used. 

Composition of the Atmosphere. Atmospheric air is not a simple 
substance but a mechanical mixture. Oxygen and nitrogen, the 
principal constituents, are present in very nearly the proportion of one 
part of oxygen to four parts of nitrogen by weight. Carbonic acid gas, 
the product of all combustion, exists in the proportion of 3 to 5 parts 
in 10,000 in the open country. Water in the form of vapor, varies 
greatly with the temperature and with the exposure of the air to open 
bodies of water. In addition to the above, there are generally present, 
in variable but exceedingly small quantities, ammonia, sulphuretted 
hydrogen, sulphuric, sulphurous, nitric, and nitrous acids, floating 
organic and inorganic matter, and local impurities. Air also contains 
ozone, which is a peculiarly active form of oxygen; and lately another 
constituent called argon has been discovered. 

Oxygen is the most important element of the air, so far as both 
heating and ventilation are concerned. It is the active element in the 
chemical process of combustion and also in the somewhat similar 
process which takes place in the respiration of human beings. Taken 
into the lungs, it acts upon the excess of carbon in the blood, and pos¬ 
sibly upon other ingredients, forming chemical compounds which are 
thrown off in the act of respiration or breathing. 

Nitrogen. The principal bulk of the atmosphere is nitrogen, 
which exists uniformly diffused with oxygen and carbonic acid gas. 
This element is practically inert in all processes of combustion or 
respiration. It is not affected in composition, either by passing through 
a furnace during combustion or through the lungs in the process of 
respiration. Its action is to render the oxygen less active, and to 
absorb some part of the heat produced by the process of oxidation. 

Carbonic acid gas is of itself only a neutral constituent of the 
atmosphere, like nitrogen; and—contrary to the general impression— 
its presence in moderately large quantities (if uncombined with other 


17 


8 


HEATING AND VENTILATION 


substances) is neither disagreeable nor especially harmful. Its 
presence, however, in air provided for respiration, decreases the readi¬ 
ness with which the carbon of the blood unites with the oxygen of the 
air; and therefore, when present in sufficient cjuantity, it may cause 
indirectly, not only serious, but fatal results. The real harm of a 
vitiated atmosphere, however, is caused by the other constituent 
gases and by the minute organisms which are produced in the process 
of respiration. It is known that these other impurities exist in fixed 
proportion to the amount of carbonic acid present in an atmosphere 
vitiated by respiration. Therefore, as the relative proportion of 
carbonic acid can easily be determined by experiment, the fixing of a 
standard limit of the amount in which it may be allowed, also limits the 
amounts of other impurities which are found in combination with it. 

When carbonic acid is present in excess of 10 parts in 10,000 
parts of air, a feeling of weariness and stuffiness,generally accompanied 
by a headache, will be experienced; while with even 8 parts in 10,000 
parts a room would be considered close. For general considerations 
of ventilation, the limit should be placed at 6 to 7 parts in 10,000, thus 
allowing an increase of 2 to 3 parts over that present in outdoor air, 
which may be considered to contain four parts in 10,000 under ordi¬ 
nary conditions. 

Analysis of Air. An accurate qualitative and quantitative 
analysis of air samples can be made only by an experienced chemist. 
There are, however, several approximate methods for determining 
the amount of carbonic acid present, which are sufficiently exact for 
practical purposes. Among these the following is one of the simplest: 

The necessary apparatus consists of six clean, dry, and tightly 
corked bottles, containing respectively 100,200, 250,300, 350, and 400 
cubic centimeters, a glass tube containing exactly 15 cubic centimeters 
to a given mark, and a bottle of perfectly clear, fresh limewater. The 
bottles should be filled with the air to be examined by means of a hand¬ 
ball syringe. Add to the smallest bottle 15 cubic centimeters of the 
limewater, put in the cork, and shake well. If the limewater has a 
milky appearance, the amount of carbonic acid will be at least 16 
parts in 10,000. If the contents of the bottle remain clear, treat the 
bottle of 200 cubic centimeters in the same manner; a milky appear¬ 
ance or turbidity in this would indicate 12 parts in 10,000. In *a 
similar manner, turbidity in the 250 cubic centimeter bottle indicates 


18 


HEATING AND VENTILATION 


9 


10 parts in 10,000; in the 300, 8 parts; in the 350, 7 parts; and in the 
400, less than 6 parts. The ability to conduct more accurate analyses 
can be attained only by special study and a knowledge of chemical 
properties and of methods of investigation. 

Another method similar to the above, makes use of a glass 
cylinder containing a given quantity of limewater and provided with a 
piston. A sample of the air to be tested is drawn into the cylinder by 
an upward movement of the piston. The cylinder is then thoroughly 
shaken, and if the limewater shows a milky appearance, it indicates 
a certain proportion of carbonic acid in the air. If the limewater 
remains clear, the air is forced out, and another cylinder full drawn in, 
the operation being repeated until the limewater becomes milky. 
The size of the cylinder and the quantity of limewater are so propor¬ 
tioned that a change in color at the first, second, third, etc., cylinder 
full of air indicates different proportions of carbonic acid. This test 
is really the same in principle as the one previously described; but the 
apparatus used is in more convenient form. 

Air Required for Ventilation. The amount of air required to 
maintain any given standard of purity can very easily be determined, 
provided we know the amount of carbonic acid given off in the process 
of respiration. It has been found by experiment that the average 
production of carbonic acid by an adult at rest is about .6 cubic foot 
per hour. If we assume the proportion of this gas as 4 parts in 10,000 
in the external air, and are to allow 6 parts in 10,000 in an occupied 
room, the gain will be 2 parts in 10,000; or, in other words, there will 
2 

be -- = .0002 cubic foot of carbonic acid mixed with each cubic 

10,000 

foot of fresh air entering the room. Therefore, if one person gives 
off .6 cubic foot of carbonic acid per hour, it will require .6 -5- .0002 
= 3,000 cubic feet of air per hour per person to keep the air in the 
room at the standard of purity assumed—that is, 6 parts of carbonic 
acid in 10,000 of air. 

Table II has been computed in this manner, and shows the 
amount of air which must be introduced for each person in order to 
maintain various standards of purity. 

While this table gives the theoretical quantities of air required 
for different standards of purity, and may be used as a guide, it will be 
better in actual practice to use quantities which experience has shown 


19 



10 


HEATING AND VENTILATION 


to give good results in different types of buildings. In auditoriums 
where the cubic space per individual is large, and in which the atmos¬ 
phere is thoroughly fresh before the rooms are occupied, and the 
occupancy is of only two or three hours’ duration, the air-supply may 
be reduced somewhat from the figures given below. 

TABLE II 


Quantity of Air Required per Person 


Standard Parts of Carbonic 
Acid in 10,000 of Air 
in Room 

Cubic Feet of Air Required per Person 

Per Minute 

Per Hour 

5 

100 

6,000 

6 

50 

3,000 

7 

33 

2,000 

8 

25 

1,500 

9 

20 

1,200 

10 

16 

1,000 


Table III represents good modern practice and may be used 
with satisfactory results: 


TABLE III 

Air Required for Ventilation of Various Classes of Buildings 


Air-Supply per Occupant for. 

Cubic Feet per 
Minute 

Cubic Feet per 
Hour 

Hospitals 

80 to 100 

4, 800 to 6, 000 

High Schools 

50 

3, 000 

Grammar Schools 

* 40 

2, 400 

Theaters and Assembly Halls 

oer. 

1, 500 

Churches 

20 

1, 200 


When possible, the air-supply to any given room should be based 
upon the number of occupants. It sometimes happens, however, 
that this information is not available, or the character of the room is 
such that the number of persons occupying it may vary, as in the case 
of public waiting rooms, toilet rooms, etc. In instances of this kind, 
the required air-volume may be based upon the number of changes 
per hour. In using this method, various considerations must be taken 
into account, such as the use of the room and its condition as to crowd¬ 
ing, character of occupants, etc. In general, the following will be 
found satisfactory for average conditions: 


20 



















HEATING AND VENTILATION 


11 


TABLE IV 


Number of Changes of Air Required in Various Rooms 


Use op Room 

Changes op Air per Hour 

Public Waiting Room 

4 to 5 

Public Toilets 

5“ 6 

Coat and Locker Rooms 

4 “ 5 

Museums 

3 “ 4 

Offices, Public 

4 “ 5 

Offices, Private 

3“ 4 

Public Dining Rooms 

4 “ 5 

Living Rooms 

3 “ 4 

Libraries, Public 

4 “ 5 

Libraries, Private 

3" 4 


Force for Moving Air. Air is moved for ventilating purposes in 
two ways: (1) by expansion due to heating; (2) by mechanical means. 
The effect of heat on the air is to increase its volume and therefore 
lessen its density or weight, so that it tends to rise and is replaced by 
the colder air below. The available force for moving air obtained in 
this way is very small, and is quite likely to be overcome by wind or 
external causes. It will be found in general that the heat used for 
producing velocity in this manner, when transformed into work in 
the steam engine, is greatly in 
excess of that required to pro¬ 
duce the same effect by the use of 
a fan. 

Ventilation by mechanical 
means is performed either by 
pressure or by suction. The for¬ 
mer is used for delivering fresh air 
into a building, and the latter for 
removing the foul air from it. _ 

Bv both processes the air is moved Fig. 1. Common Form of Anemometer, for 
* * Measuring Velocity of Air-Ciirrents. 

without change in temperature, 

and the force for moving must be sufficient to overcome the effects 
of wind or changes in outside temperature. Some form of fan is used 
for this purpose. 

Measurements of Velocity. The velocity of air in ventilating 
ducts and flues is measured directly by an instrument called an ane¬ 
mometer. A common form of this instrument is shown in Fig. 1. It 
consists of a series of flat vanes attached to an axis, and a series of dials. 



21 







12 


HEATING AND VENTILATION 

The revolution of the axis causes motion of the hands in proportion to 
the velocity of the air, and the result can be read directly from the dials 
for any given period. 

For approximate results the anemometer may be slowly moved 
across the opening in either vertical or horizontal parallel lines, so 
that the readings will be made up of velocities taken from all parts of 
the opening. For more accurate work, the opening should be divided 
into a number of squares by means of small twine, and readings taken 
at the center of each. The mean of these readings will give the 
average velocity of the air through the entire opening. 

AIR DISTRIBUTION 

The location of the air inlet to a room depends upon the size of 
the room and the purpose for which it is used. In the case of living 
rooms in dwelling-houses, the registers are placed either in the floor 
or in the wall near the floor; this brings the warm air in at the coldest 
part of the room and gives an opportunity for warming or drying the 
feet if desired. In the case of schoolrooms, where large volumes of 
warm air at moderate temperatures are required, it is best to discharge 
it through openings in the wall at a height of 7 or 8 feet from the floor; 
this gives a more even distribution, as the warmer air tends to rise and 
hence spreads uniformly under the ceiling; it then gradually displaces 
other air, and the room becomes filled with pure air without sensible 
currents or drafts. The cooler air sinks to the bottom of the room, and 
can be taken off through ventilating registers placed near the floor. 
The relative positions of'the inlet and outlet are often governed to 
some extent by the building construction; but, if possible, they should 
both be located in the same side of the room. Figs. 2, 3, and 4 show 
common arrangements. 

The vent outlet should always, if possible, be placed in an inside 
wall; otherwise it will become chilled and the air-flow through it will 
become sluggish. In theaters and churches which are closely packed, 
the air should enter at or near the floor, in finely-divided streams; and 
the discharge ventilation should be through openings in the ceiling. 
The reason for this is the large amount of animal heat given off from 
the bodies of the audience; this causes the air to become still further 
heated after entering the room, and the tendency is to rise continuously 

22 




HEATING AND VENTILATION 


13 


from floor to ceiling, thus carrying away all impurities from respiration 
as fast as they are given off. 

All audience halls in which the occupants are closely seated should 
be treated in the same manner, when possible. This, however, can¬ 
not always be done, as the seats are often made removable so that the 



outs/de wall outside wall outside wall 

Fig. 2. Fig. 3. Fig. 4. 

Diagrams Showing Relative Positions of Air Inlets and Outlets as Commonly Arranged. 


floor can be used for other purposes. In cases of this kind, part of 
the air may be introduced through floor registers placed along the outer 
aisles, and the remainder by means of wall inlets the same as for school¬ 
rooms. The discharge ventilation should be partly through registers 
near the floor, supplemented by ample ceiling vents for use when the 
hall is crowded or the outside temperature high. 

The matter of air-velocities, size of flues, etc., will be taken up 
under the head of “Indirect Heating.” 

HEAT LOSS FROM BUILDINGS 

A British Thermal Unit , or B. T. U., has been defined as the 
amount of heat required to raise the temperature of one pound of 
water one degree F. This measure of heat enters into many of the 
calculations involved in the solving of problems in heating and ventila¬ 
tion, and one should familiarize himself with the exact meaning of 
the term. 

Causes of Heat Loss. The heat loss from a building is due to 
the following causes: (1) radiation and conduction of heat through 
walls and windows; (2) leakage of warm air around doors and win¬ 
dows and through the walls themselves; and (3) heat required to warm 
the air for ventilation. 

Loss through Walls and Windows. The loss of heat through 
the walls of a building depends upon the material used in construction 


23 



















14 


HEATING AND VENTILATION 


TABLE V 

Heat Losses in B. T. U. per Square Foot of Surface per Hour— 
Southern Exposure 


Material 

Difference between Inside 
side Temperatures 

AND 

Out- 

10° 

20° 

30° 

40° 

50° 

60° 

70° 

80° 

90° 

100° 

8-in. Brick Wall. 

5 

9 

13 

18 

22 

27 

31 

36 

40 

45 

12-in. Brick Wall .. 

4 

7 

10 

13 

16 

20 

23 

26 

30 

33 

16-in. Brick Wall. 

3 

5 

8 

10 

13 

16 

19 

22 

24 

27 

20-in. Brick Wall.. 

2.8 

4.5 

7 

9 

11 

14 

16 

18 

20 

23 

24-in. Brick Wall. 

2.5 

4 

6 

8 

10 

12 

14 

16 

18 

20 

28-in. Brick Wall. 

2 

3.5 

5 

n 

9 

11 

13 

14 

16 

18 

32-in. Brick Wall. 

1.5 

3 

4.5 

6 

8 

10 

11 

13 

15 

16 

Single Window*. 

12 

24 

36 

49 

60 

73 

85 

93 

110 

122 

Double Window.. 

8 

16 

24 

32 

40 

48 

56 

62 

70 

78 

Single Skylight. 

11 

21 

31 

42 

52 

63 

73 

84 

94 

104 

Double Skylight... 

7 

14 

20 

28 

35 

42 

48 

56 

62 

70 

1-in. Wooden Door. 

4 

8 

12 

16 

20 

24 

28 

32 

36 

40 

2-in. Wooden Door. 

3 

5 

8 

11 

14 

17 

20 

23 

25 

28 

2-in. Solid Plaster Partition...... 

6 

12 

18 

24 

30 

36 

42 

48 

54 

60 

3-in. Solid Plaster Partition. 

5 

10 

15 

20 

25 

30 

35 

40 

18 

45 

50 

Concrete Floor on Brick Arch.... 

2 

4 

6.5 

9 

11 

13 

15 

20 

22 

Wood Floor on Brick Arch. 

1.5 

3 

4.5 

6 

7 

9 

10 

12 

13 

15 

Double Wood Floor... 

Walls of Ordinary Wooden 

1 

2 

3 

4 

5 

6 

7 

8 

! 9 

10 

Dwellings.. 

3 

5 

8 

10 

13 

16 

19 

22 

24 

27' 


For solid stone walls, multiply the figures for brick of the same thickness 
by 1.7. Where rooms have a cold attic above or cellar beneath, multiply the 
heat loss through walls and windows by 1.1. 

Correction for Leakage. The figures given in the above table apply only 
to the most thorough construction. For the average well-built house, the 
results should be increased about 10 per cent; for fairly good construction, 
20 per cent; and for poor construction, 30 per cent. 

Table V applies only to a southern exposure; for other exposures multi¬ 
ply the heat loss given in Table V by the factors given in Table VI. 

of the wall, the thickness, the number of layers, and the difference 
between the inside and outside temperatures. The exact amount of 
heat lost in this way is very difficult to determine theoretically, hence 
we depend principally on the results of experiments. 

Loss by Air-Leakage. The leakage of air from a room varies 
from one to two or more changes of the entire contents per hour, 
depending upon the construction, opening of doors, etc. It is com¬ 
mon practice to allow for one change per hour in well-constructed 
buildings where two walls of the room have an outside exposure. As 
the amount of leakage depends upon the extent of exposed wall and 
window surface, the simplest way of providing for this is to increase 


24 





















































HEATING AND VENTILATION 


15 


TAELE VI 

Factors for Calculating Heat Loss for Other than Southern Exposures 


Exposure 

Factor 

N. 

1.32 

E. 

1.12 

S. 

1.0 

w. 

1.20 

N. E. 

1.22 

N. W. 

1.26 

S.E. 

1.06 

s. w. 

1.10 

N., E., S., and W., or total exposure 

1.16 


the total loss through walls and windows by a factor depending upon 
the tightness of the building construction. Authorities differ con¬ 
siderably in the factors given for heat losses, and there are various 
methods for computing the same. The figures given in Table V have 
been used extensively in actual practice, and have been found to give 
good results when used with judgment. The table gives the heat losses 
through different thicknesses of walls, doors, windows, etc., in B. T. 
U., per square foot of surface per hour, for varying differences in inside 
and outside temperatures. 

In computing the heat loss through walls, only those exposed to 
the outside air are considered. 

In order to make the use of the table clear, we shall give a num¬ 
ber of examples illustrating its use: 

Example 1. Assuming an inside temperature of 70°, what will be the 
heat loss from a room having an exposed w T all surface of 200 square feet and a 
glass surface of 50 square feet, when the outside temperature is zero? The 
wall is of brick, 16 inches in thickness, and has a southern exposure; the win¬ 
dows are single; and the construction is of the best, so that no account need 
be taken of leakage 

We find from Table V, that the factor for a 16-inch brick wall 
with a difference in temperature of 70° is 19, and that for glass (single 
window) under the same condition is 85; therefore. 

Loss through walls = 200 X 19 = 3,800 

Loss through windows = 50 X 85 = 4,250 

Total loss per hour = 8,050 B.T.U. 

Example 2. A room 15 ft. square and 10 ft. high has two exposed walls, 
one toward the north, and the other toward the west. There are 4 windows, 
each 3 feet by 6 feet in size. The two in the north wall are double, while the 


25 











16 


HEATING AND VENTILATION 


other two are single. The walls are of brick, 20 inches in thickness. With an 
inside temperature of 70°, what will be the heat loss per hour when it is 10° 
below zero? 

Total exposed surface =15X10X2 = 300 
Glass surface = 3 X 6X4= 72 

Net wall surface = 228 

Difference between inside and outside temperature 80°. 

Factor for 20-inch brick wall is 18. 

Factor for single window is 93. 

Factor for double window is 62. 

The heat losses are as follows: 

Wall, 228 X 18 = 4,104 

Single windows, 36 X 93 = 3,348 
Double windows, 36 X 62 = 2,232 

9,684 B.T. U. 

As one side is toward the north, and the other toward the west, the 
actual exposure is N. W. Looking in Table VI, we find the correction 
factor for this exposure to be 1.26; therefore the total heat loss is 
9,684 X 1.26 = 12,201.84 B.T.U. 

Example 3, A dwelling-house of fair wooden construction measures 
160 ft. around the outside; it has 2 stories, each 8 ft. in height; the windows 
are single, and the glass surface amounts to one-fifth the total exposure; the 
attic and cellar are unwarmed. If 8,000 B. T. U. are utilized from each pound 
of coal burned in the furnace, how many pounds will be required per hour to 
maintain a temperature of 70° when it is 20° above zero outside? 

Total exposure = 160 X 16 = 2,560 
Glass surface = 2,560 -5- 5 = 512 

Net wall = 2,048 

Temperature difference = 70 — 20 = 50° 

Wall 2,048 X 13 = 26,624 

Glass 512 X 60 = 30,720 


57,344B.T. U. 

As the building is exposed on all sides, the factor for exposure will be 
the average of those for N., E., S., and W., or 

(1.32 + 1.12 + 1.0 + 1.20) -r- 4 = 1.16 
The house has a cold cellar and attic, so we must increase the heat loss 


26 









HEATING AND VENTILATION 


17 


10 per cent for each of the first two conditions, and 20 per cent for the 
last. Making these corrections we have: 

57,344 X 1.16 X 1.10 X 1.10 X 1.20 = 96,338 B.T.U. 

If one pound of coal furnishes 8,000 B. T. U., then 96,338 -r- 8,000 = 
12 pounds of coal per hour required to warm the building to 70° 
under the conditions stated. 

Approximate Method. For dwelling-houses of the average con¬ 
struction, the following simple method for calculating the heat loss 
may be used. Multiply the total exposed surface by 45, which will 
give the heat loss in B. T. U. per hour for an inside temperature of 70° 
in zero weather. 

This factor is obtained in the following manner: Assume the glass 
surface to be one-sixth the total exposure, which is an average propor¬ 
tion. Then each square foot of exposed surface consists one-sixth 
of glass and five-sixths of wall, and the heat loss for 70° difference in 
temperature would be as follows: 

Wall 4X19= 15.8 
6 

Glass -i- X 85 = 14.1 
29.9 

Increasing this 20 per cent for leakage, 16 per cent fof exposure, and 
10 per cent for cold ceilings, we have: 

29.9 X 1.20 X 1.16 X 1.10 = 45. 

The loss through floors is considered as being offset by including 
the kitchen walls of a dwelling-house, which are warmed by the range, 
and which would not otherwise be included if computing the size of a 
furnace or boiler for heating. 

If the heat loss is required for outside temperatures other than 
zero, multiply by 50 for 10 degrees below, and by 40 for 10 degrees 
above zero. 

This method is convenient for approximations in the case of 
dwelling-houses; but the more exact method should be used for other 
types of buildings, and in all cases for computing the heating surface 
for separate rooms. T Vhen calculating the heat loss from isolated 
rooms , the cold inside walls as well as the outside must be considered. 

The loss through a wall next to a cold attic or other un warmed space 
may in general be taken as about two-thirds that of an outside wall. 


27 





18 


HEATING AND VENTILATION 


Heat Loss by Ventilation. One B. T. U. will raise the tempera¬ 
ture of 1 cubic foot of air 55 degrees at average temperatures and 
pressures, or will raise 55 cubic feet 1 degree, so that the heat required 
for the ventilation of any room can be found by the following formula: 
Cu. ft. of air per hour X Number of degrees rise _ g rp re q U j re( j 
55 

To compute the heat loss for any given room which is to be 
ventilated, first find the loss through walls and windows, and correct 
for exposure and leakage; then compute the amount required for 
ventilation as above, and take the sum of the two. An inside tem¬ 
perature of 70° is always assumed unless otherwise stated. 

Examples. What quantity of heat will be required to warm 100,000 
cubic feet of air to 70° for ventilating purposes when the outside temperature 
is 10 below zero? 

100,000 X 80 55 = 145,454 B. T. U. 

How many B. T. U. will be required per hour for the ventilation of a 
church seating 500 people, in zero weather? 

Referring to Table III, we find that the total air required per 
hour is 1,200 X 500 = 600,000 cu. ft.; therefore 600,000 X 70 -5- 55 
= 763 636 B. T. U. 


The factor Rise ^ Temperature ^ approximately u for GO o, 
oo 


1.3 for 70°, and 1.5 for 80°. Assuming a temperature of 70° for the 
entering air, we may multiply the air-volume supplied for ventilation 
by 1.1 for an outside temperature of 10° above 0, by 1.3 for zero, and 
by 1.5 for 10° below zero—which covers the conditions most commonly 
met with in practice. 


EXAMPLES FOR PRACTICE 

1. A room in a grammar school 28 ft. by 32 ft. and 12 feet high is 
to accommodate 50 pupils. The walls are of brick 16 inches in thick¬ 
ness; and there.are 6 single windows in the room, each 3 ft. by 6 ft.: 
there are warm rooms above and below; the exposure is S. E. How 
many B. T. U. will be required per hour for warming the room, and 
how many for ventilation, in zero weather, assuming the building to 
be of average construction? 

Ans. 22,056 + for warming; 152,727 -f for ventilation. 

2. A stone church seating 400 people has walls 20 inches in 
thickness. It has a wall exposure of 5,000 square feet, a glass expos- 


28 







HEATING AND VENTILATION 


19 


i tf re (single windows) of 600 square feet, and a roof exposure of 7,000 
square feet; the roof is of 2-inch pine plank, and the factor for heat 
loss may be taken the same as for a 2-inch wooden door. The floor 
is of wood on brick arches, and has an area of 4,000 square feet. The 
building is exposed on all sides, and. is of first-class construction. 
What will be the heat required per hour for both warming and ventila¬ 
tion when the outside temperature is 20° above zero? 

Ans. 296,380 for warming; 436,363 + for ventilation. 

3. A dwelling-house of average wooden construction measures 
200 feet around the outside, and has 3 stories, each 9 feet high. 
Compute the heat loss by the approximate method when the tem¬ 
perature is 10° below zero. 

Ans. 270,000 B. T. U. per hour. 

FURNACE HEATING 

In construction, a furnace is a large stove with a combustion 
chamber of ample size over the fire, the whole being inclosed in a 
casing of sheet iron or brick. The bottom of the casing is provided 
with a cold-air inlet, and at the top are pipes which connect with 
registers placed in the various rooms to be heated. Cold, fresh air 
is brought from out of doors through a pipe or duct called the cold-air 
box; this air enters the space between the casing and the furnace near 
the bottom, and, in passing over the hot surfaces of the fire-pot and 
combustion chamber, becomes heated. It then rises through the 
warm-air pipes at the top of the casing, and is discharged through the 
registers into the rooms above. 

As the warm air is taken from the top of the furnace, cold air 
flows in through the cold-air box to take its place. The air for heating 
the rooms does not enter the combustion chamber. 

Fig. 5 shows the general arrangement of a furnace with its con¬ 
necting pipes. The cold-air inlet is seen at the bottom, and the hot-air 
pipes at the top; these are all provided with dampers for shutting off or 
regulating the amount of air flowing through them. The feed or fire 
door is shown at the front, and the ash door beneath it; a water-pan is 
placed inside the casing, and furnishes moisture to the warm air before 
passing into the rooms; water is either poured into the pan through an 
opening in the front, provided for this purpose, or is supplied auto¬ 
matically through a pipe. 


29 




20 


HEATING AND VENTILATION 


The fire is regulated by means of a draft slide in the ash door, and 
a cold-air or regulating damper placed in the smoke-pipe. Clean-out 
doors are placed at different points in the casing for the removal of 



ashes and soot. Furnaces are made either of cast iron, or of wrought- 
iron plates'riveted together and provided with brick-lined firepots. 

Types of Furnaces. Furnaces may be divided into two general 


30 


















































HEATING AND VENTILATION 


21 


types known as direct-draft and indirect-draft. Fig. G shows in section 
a common form of direct-draft furnace; the better class have a radi¬ 
ator, generally placed at the top, through which the gases pass before 
reaching the smoke-pipe. They have but one damper, usually 
combined with a cold-air check. Many of the cheaper direct-draft 



Fig. 6. Section through Direct-Draft Furnace. 
Courtesy of Fuller-Warren Company, Milwaukee, Wisconsin. 


furnaces have no radiator at all, the gases passing directly into the 
smoke-pipe and carrying away much heat that should be utilized. 

The furnace shown in Fig. 6 is made of cast iron and has a large 
radiator at the top; the smoke connection is shown at the rear. 

Fig. 7 represents another form of direct-draft furnace. In this 
case the radiator is made of sheet-steel plates riveted together with 
tubular flues passing through it. 

In the ordinary indirect-draft type of furnace (see Fig. 8), the 
gases pass downward through flues to a radiator located near the base, 


31 











22 


HEATING AND VENTILATION 


thence upward through another flue to the smoke-pipe. In addition ij 
to the damper in the smoke-pipe, a direct-draft damper is required J 
to give direct connection with the funnel when coal is first put on, to ! 
facilitate the escape of gas to the chimney. When the chimney draft 



Stewart “B” Direct-Draft Furnace with Tubular Steel Radiator. 
Portable Form for Hard or Soft Coal. 


Fig. 7. 

Courtesy of Fuller-Warren Company, Milwaukee, Wisconsin. 


is weak, trouble from gas is more likely to be experienced with fur 
naces of this type than with those having a direct draft. 

Grates. No part of a furnace is of more importance than the 
grates. The plain grate rotating about a center pin was for a long 
time the one most commonly used. These grates were usually pro¬ 
vided with a clinker door for removing any refuse too large to pass 
between the grate bars. The action of such grates tends to leave a 


32 














HEATING AND VENTILATION 


23 


cone of ashes in the center of the fire causing it to burn more freely 
around the edges. A better form of grate is the revolving triangular 
pattern, which is now used in many of the leading furnaces. It con¬ 
sists of a series of triangular bars having teeth. The bars are con¬ 
nected by gears, and are turned by means of a detachable lever. If 



Fig. 8. Indirect-Draft Type of Furnace. Gases Pass Downward to Radiator at Bottom, 
Thence Upward to Smoke-Pipe. 


properly used, this grate will cut a slice of ashes and clinkers from 
under the entire fire with little, if any loss of unccnsumed coal. 

The Firepot. Firepots are generally made of cast iron or of steel 
plate lined with firebrick. The depth ranges from about 12 to 18 
inches. In cast-iron furnaces of the better class, the firepot is made 
very heavy, to insure durability and to render it less likely to become 
red-hot. The firepot is sometimes made in two pieces, to reduce the 


33 

































































24 


HEATING AND VENTILATION 


liability to cracking. The heating surface is sometimes increased by 
corrugations, pins, or ribs. 

A firebrick lining is necessary in a wrought-iron or steel furnace 
to protect the thin shell from the intense heat of the fire. Since brick- 
lined firepots are much less effective than cast-iron in transmitting 
heat, such furnaces depend to a great extent for their efficiency on the 
heating surface in the dome and radiator; and this, as a rule, is much 
greater than in those of cast iron. 

Cast-iron furnaces have the advantage when coal is first put on 
(and the drop flues and radiator are cut out by the direct damper) of 
still giving off heat from the firepot, while in the case of brick linings 
very little heat is given off in this way, and the rooms are likely to 
become somewhat cooled before the fresh coal becomes thoroughly 
ignited. 

Combustion Chamber. The body of the furnace above the fire- 
pot, commonly called the dome or feed section, provides a combustion 
chamber. This chamber should be of sufficient size to permit the 
gases to become thoroughly mixed with the air passing up through the 
fire or entering through openings provided for the purpose in the feed 
door. In a well-designed furnace, this space should be somewhat 
larger than the firepot. 

Radiator. The radiator, so called, with which all furnaces of 
the better class are provided, acts as a sort of reservoir in which the 
gases are kept in contact with the air passing over the furnace until 
they have parted with a considerable portion of their heat. Radiators 
are built of cast iron, of steel plate, or of a combination of the two. 
The former is more durable and can be made with fewer joints, but 
owing to the difficulty of casting radiators of large size, steel plate is 
commonly used for the sides. 

The effectiveness of a radiator depends on its form, its heating 
surface, and the difference between the temperature of the gases and 
the surrounding air. Owing to the accumulation of soot, the bottom 
surface becomes practically worthless after the furnace has been in 
use a short time; surfaces, to be effective, must therefore be self¬ 
cleaning. 

If the radiator is placed near the bottom of the furnace the gases 
are surrounded by air at the lowest temperature, which renders the 
radiator more effective for a given size than if placed near the top and 


34 


HEATING AND VENTILATION 


25 


surrounded by warm air. On the other hand, the cokl air has a ten¬ 
dency to condense the gases, and the acids thus formed are likely to 
corrode the iron. 

Heating Surface. The different heating surfaces may be de¬ 
scribed as follows: Firepot surface; surfaces acted upon by direct 
rays of heat from the fire, such as the dome or combustion chamber; 
gas- or smoke-heated surfaces, such as flues or radiators; and ex¬ 
tended surfaces, such as pins or ribs. Surfaces unlike in character 
and location, vary greatly in heating power, so that, in making com¬ 
parisons of different furnaces, we must know the kind, form, and 
location of the heating surfaces, as well as the area. 

In some furnaces having an unusually large amount of surface, 
it will be found on inspection that a large part would soon become 
practically useless from the accumulation of soot. In others a large 
portion of the surface is lined with firebrick, or is so situated that the 
air-currents are not likely to strike it. 

The ratio of grate to heating surface varies somewhat according 
to the size of furnace. It may be taken as 1 to 25 in the smaller sizes, 
and 1 to 15 in the larger. 

Efficiency. One of the first items to be determined in esti¬ 
mating the heating capacity of a furnace, is its efficiency—that is, 
the proportion of the heat in the coal that may be utilized for warming. 
The efficiency depends chiefly on the area of the heating surface as 
compared with the grate, on its character and arrangement, and on 
the rate of combustion. The usual proportions between grate and 
heating surface have been stated. The rate of combustion required 
to maintain a temperature of 70° in the house, depends, of course, 
on the outside temperature. In very cold weather a rate of 4 to 5 
pounds of coal per square foot of grate per hour must be main¬ 
tained. 

One pound of good anthracite coal will give off about 13,000 
B. T. U., and a good furnace should utilize 70 per cent of this heat. 
The efficiency of an ordinary furnace is often much less, sometimes 
as low as 50 per cent. 

In estimating the required size of a first-class furnace with good 
chimney draft, we may safely count upon a maximum combustion 
of 5 pounds of coal per square foot of grate per hour, and may assume 
that 8,000 B. T. U. will be utilized for warming purposes from each 


35 




26 


HEATING AND VENTILATION 


pound burned. This quantity corresponds to an efficiency of 60 
per cent. 

Heating Capacity. Having determined the heat loss from a 
buih ling by the methods previously given, it is a simple matter to 
compute the size of grate necessary to burn a sufficient quantity of 
coal to furnish the amount of heat required for warming. 

In computing the size of furnace, it is customary to consider the 
whole house as a single room, with four outside walls and a cold attic. 
The heat losses by conduction and leakage are computed, and in¬ 
creased 10 per cent for the cold attic, and 16 per cent for exposure. 
The heat delivered to the various rooms may be considered as being 
made up of two parts— first, that required to warm the outside air 
up to 70° (the temperature of the rooms); and second, the quantity 
which must be added to this to offset the loss by conduction and leak¬ 
age. Air is usually delivered through the registers at a temperature 
of 120°, with zero conditions outside, in the best class of residence 


70 

work; so that of the heat given to the entering air may be con¬ 
sidered as making up the first part, mentioned above, leaving 
available for purely heating purposes. From this it is evident that 


the heat supplied to the entering air must be equal to 1 


50 

120 


= 2.4 


times that required to offset the loss by conduction and leakage. 

Example. The loss through the walls and windows of a building is 
found to be 80,000 B. T. U. per hour in zero weather. What will be the size 
of furnace required to maintain an inside temperature of 70 degrees? 


From the above, we have the total heat required, equal to 80,000 
X 2.4 = 192,000 B. T. U. per hour. If we assume that 8,000 B. T. 
U. are utilized per pound of coal, then 192,000 4- 8,000 = 24 pounds 
of coal required per hour; and if 5 pounds can be burned on each 


square foot of grate per hour, then 


24 

5 


= 4.8 square feet required. 


A grate 30 inches in diameter has an area of 4.9 square feet, and is the 
size we should use. 

When the outside temperature is taken as 10° below zero, multi¬ 
ply by 2.6 instead of 2.4; and multiply by 2.8 for 20° below. 

Table VII will be found useful in determining the diameter of 
firepot required. 


36 


HEATING AND VENTILATION 


27 


TABLE VII 
Firepot Dimensions 


1' ■ — 

Average Diameter of Grate, in Inches 

Area in Square Feet 

18 

1.77 

20 

2.18 

22 

2.64 

24 

3.14 

26 

3.69 

28 

4.27 

30 

4.91 

32 

5.58 


EXAMPLES FOR PRACTICE 

1. A brick apartment house is 20 feet wide, and has 4 stories, 

each being 10 feet in height. The house is one of a block, and is 
exposed only at the front and rear. The walls are 16 inches thick, 
and the block is so sheltered that no correction need be made for 
exposure. Single windows make up J the total exposed surface. 
Figure for cold attic but warm basement. What area of grate surface 
will be required for a furnace to keep the house at a temperature of 
70° when it is 10° below zero outside? Ans. 3.5 square feet. 

2. A house having a furnace with a firepot 30 inches in diameter, 
is not sufficiently warmed, and it is decided to add a second furnace 
to be used in connection with the one already in. The heat loss from 
the building is found by computation to be 133,600 B. T. U. per hour, 
in zero weather. What diameter of firepot will be required for the 

extra furnace? Ans - 24 inches * 

Location of Furnace. A furnace should be so placed that the 
warm-air pipes will be of nearly the same length. The air travels 
most readily through pipes leading toward the sheltered side of the 
house and to the upper rooms. Therefore pipes leading toward the 
north or west, or to rooms on the first floor, should be favored in 
| regard to length and size. The furnace should be placed somewhat 
to the north or west of the center of the house, or toward the points 
of compass from which the prevailing winds blow. 

Smoke=Pipes. Furnace smoke-pipes range in size from about 
6 inches in the smaller sizes to 8 or 9 inches in the larger ones. They 
are generally made of galvanized iron of No. 24 gauge or heavier. 
The pipe should be carried to the chimney as directly as possible, 


37 








28 


HEATING AND VENTILATION 


avoiding bends which increase the resistance and diminish the draft. 
Where a smoke-pipe passes through a partition, it should be pro¬ 
tected by a soapstone or double-perforated metal collar having a 
diameter at least 8 inches greater than that of the pipe. The top of 
the smoke-pipe should not be placed within 8 inches of unprotected 
beams, nor less than 6 inches under beams protected by asbestos or 
plaster with a metal shield beneath. A collar to make tight con¬ 
nection with the chimney should be riveted to the pipe about 5 inches 
from the end, to prevent the pipe being pushed too far into the flue. 
Where the pipe is of unusual length, it is well to cover it to prevent 
loss of heat and the condensation of smoke. 

Chimney Flues. Chimney flues, if built of brick, should have 
walls 8 inches in thickness, unless terra-cotta linings are used, when 
only 4 inches of brickwork is required. Except in small houses 
where an 8 by 8-inch flue may be used, the nominal size of the smoke 
flue should be at least 8 by 12-inches, to allow for contractions or off¬ 
sets. A clean-out door should be placed at the bottom of the flue, 
for removing ashes and soot. A square flue cannot be reckoned at 
its full area, as the corners are of little value. To avoid down drafts, 
the top of the chimney must be carried above the highest point of the 
roof unless provided with a suitable hood or top. 

Cold=Air Box. The cold-air box should be large enough to 
supply a volume of air sufficient to fill all the hot-air pipes at the same 
time. If the supply is too small, the distribution is sure to be unequal, 
and the cellar will become overheated from lack of air to carry away 
the heat generated. 

If a box is made too small, or is throttled down so that the volume 
of air entering the furnace is not large enough to fill all the pipes, 
it will be found that those leading to the less exposed side of the 
house or to the upper rooms will take the entire supply, and that 
additional air to supply the deficiency will be drawn down through 
registers in rooms less favorably situated. It is common practice 
to make the area of the cold-air b^x three-fourths the combined 
area of the hot-air pipes. The inlet should be placed where the 
prevailing cold winds will blow into it; this is commonly on the north 
or west side of the house. If it is placed on the side away from the 
wind, warm air from the furnace is likely to be drawn out thiough 
the cold-air box. 


38 


HEATING AND VENTILATION 


29 


- FOR RETURNING 
{AIR FROM ABOVE 


Whatever may be the location of the entrance to the cold-air 
box, changes in the direction of the wind may take place which will 
bring the inlet on the wrong side of the house. To prevent the 
possibility of such changes affecting the action of the furnace, the 
cold-air box is sometimes extended through the house and left open 
at both ends, with check-dampers arranged to prevent back-drafts. 
These checks should be placed some distance from the entrance, to 
prevent their becoming clogged with snow or sleet. 

The cold-air box is generally made of matched boards; but 
galvanized iron is much better; it costs more than wood, but is well 
worth the extra, expense on account of tightness, which keeps the dust 
and ashes from being drawn into the furnace casing to be discharged 
through the registers into the rooms above. 

The cold-air inlet should be covered with galvanized wire netting 
with a mesh of at least three-eighths of an inch. The frame to which 
it is attached should not 
be smaller than the in¬ 
side dimensions of the 
cold-air box. A door to 
admit air from the cellar 
to the cold-air box is 
generally provided. As 
a rule, air should be 
taken from this source, 
only when the house is 
temporarily unoccupied 
or during high winds. 

Return Duct. In 
some cases it is desirable 
to return air to the fur¬ 
nace from the rooms 
above, to be reheated. Ducts for this purpose are common in places 
where the winter temperature is frequently below zero. Return 
ducts when used, should be in addition to the regular cold-air box. 
Fig. 9 shows a common method of making the connection between 
the two. By proper adjustment of the swinging damper, the air can 
be taken either from out of doors or through the register from the 
room above. The return register is often placed in the hallway of 



Fig 9 


Common Method of Connecting Return Duct to 
Cold-Air Box. 


39 



















30 


HEATING AND VENTILATION 


a house, so that it will take the cold air which rushes in when the 
door is opened and also that which may leak in around it while 
closed. Check-valves or flaps of light gossamer or woolen cloth 
should be placed between the cold-air box and the registers to pre- j 
vent back-drafts during winds. 

The return duct should not be used too freely at the expense of 
outdoor air, and its use is not recommended except during the night 
when air is admitted to the sleeping rooms through open windows, i 

Warm=Air Pipes. The required size of the warm-air pipe to 
any given room, depends on the heat loss from the room and on the 
volume of warm air required to offset this loss. Each cubic foot of 
air warmed from zero to 120 degrees brings into a room 2.2 B. T. U. 
We have already seen that in zero weather, with the air entering the 


registers at 120 degrees, only 


— of the heat contained in the air is 
120 


available for offsetting the losses by radiation and conduction, so that 
50 

only 2.2 X = .9 B. T. U. in each cubic foot of entering air can 

be utilized for warming purposes. Therefore, if we divide the com¬ 
puted heat loss in B. T. U. from a room, by .9, it will give the number 
of cubic feet of air at 120 degrees necessary to warm the room in zero 
weather. 

As the outside temperature becomes colder, the quantity of heat 
brought in per cubic foot of air increases; but the proportion avail¬ 
able for warming purposes becomes less at nearly the same rate, so 


TABLE VIII 

Warm=Air Pipe Dimensions 


Diameter of Pipe, 
in Inches 

Area 

in Square Inches 

Area 

in Square Feet 

6 

28 

.196 

7 

•38 

.267 

8 

50 

.349 

9 

64 

.442 

10 

79 

.545 

11 

95 

.660 

12 

113 

.785 

13 

133 

.922 

14 

154 

1.07 

15 

177 

1.23 

16 

201 

1.40 


40 











HEATING AND VENTILATION 


31 


that for all practical purposes we may use the figure .9 for all usual 
conditions. In calculating the size of pipe required, we may assume 
maximum velocities of 260 and 380 feet per minute for rooms on the 
first and second floors respectively. Knowing the number of cubic 
feet of air per minute to be delivered, we can divide it by the velocity, 
which will give us the required area of the pipe in square feet. 

Round pipes of tin or galvanized iron are used for this purpose. 
Table VIII will be found useful in determining the required diameters 
of pipe in inches. 

Example. The heat loss from a room on the second floor is 18,000 B. 
T. U. per hour. What diameter of warm-air pipe will be required? 

18,000 -7- .9 = 20,000 = cubic feet of air required per hour. 
20,000 -T- 60 = 333 per minute. Assuming a velocity of 380 feet 
per minute, we have 333 380 = .87 square foot, which is the 

area of pipe required. Referring to Table VIII, we find this comes 
between a 12-inch and a 13-inch pipe, and the larger size would 
probably be chosen. 

EXAMPLES FOR PRACTICE 

1. A first-floor room has a computed loss of 27,000 B. T. U. 
per hour when it is 10° below zero. The air for warming is to enter 
through two pipes of equal size, and at a temperature of 120 degrees. 
What will be the required diameter of the pipes? 

Ans. 14 inches. 

2. If in the above example the room had been on the second 
floor, and the air was to be delivered through a single pipe, what 
diameter would be required? 

Ans. 16 inches. 

Since long horizontal runs of pipe increase the resistance and 
loss of heat, they should not in general be over 12 or 14 feet in length. 
This applies especially to pipes leading to rooms on the first floor, 
or to those on the cold side of the house. Pipes of excessive length 
should be increased in size because of the added resistance. 

Figs. 10 and 11 show common methods of running the pipes in 
the basement. The first gives the best results, and should be used 
where the basement is of sufficient height to allow it. A damper 
should be placed in each pipe near the furnace, for regulating the flow 
of air to the different rooms, or for shutting it off entirely when desired. 


41 






32 


HEATING AND VENTILATION 


While round pipe risers give the best results, it is not always 
possible to provide a sufficient space for them, and flat or oval pipes 
are substituted. When vertical pipes must be placed in single par- ' 
titions, much better results will be obtained if the studding can be 




Common Methods of Running Hot-Air Pipes in Basement. Method Shown in Fig. 10 
is Preferable where Feasible. 

made 5 or 6 inches deep instead of 4 as is usually done. Flues should 
never in any case be made less than 3J inches in depth. Each room 
should be heated by a separate pipe. In some cases, however, it is 
allowable to run a single riser to heat two unimportant rooms on an 
upper floor. A clear space of at least J inch should be left between 
the risers and studs, and the latter should be carefully tinned, and the 

TABLE IX 


Dimensions of Oval Pipes 


Dimension of Pipe 

Area in Square Inches 

6 ovaled to 5 in. 

27 

7 

tt 

a 

4 “ 

31 

7 

it 

it 

3£ “ 

29 

7 

it 

it 

6 “ 

38 

8 

a 

it 

5 “ 

43 

9 

a 


4 “ 

45 

9 

if 

it 

6 “ 

57 

9 

it 

a 

5 “ 

51 

10 

it 

tt 

3£ “ 

46 

11 

it 

it 

4 “ 

58 

12 

u 

it 

3* “ 

55 

10 

tt 

tt 

6 “ 

67 

11 

tt 

tt 

5 “ 

67 

14 

tt 

tt 

4 “ 

76 

15 

a . 

it 

31 “ 

73 

12 

a 

ft 

6 “ 

85 

12 

a 

tt 

5 “ 

75 

19 

it 

tt 

4 “ 

96 

20 

it 

tt 

31 “ 

100 


42 































HEATING AND VENTILATION 


33 


space between them on both sides covered with tin, asbestos, or wire 
lath. 

Table IX gives the capacity of oval pipes. A 6-inch pipe ovaled 
to 5 means that a 6-inch pipe has been flattened out to a thickness of 
5 inches, and column 2 gives the resulting area. 

Having determined the size of round pipe required, an equiva¬ 
lent oval pipe can be selected from the table to suit the space available. 

Registers. The registers which control the supply of warm 
air to the rooms, generally have a net area equal to two-thirds of their 
gross area. The net area should be from 10 to 20 per cent greater 
than the area of the pipe' connected with it. It is common practice 
to use registers having the short dimensions equal to, and the long 
dimensions about one-half greater than, the diameter of the pipe. 
This would give standard sizes for different diameters of pipe, as 
listed in Table X. 

TABLE X 


Sizes of Registers for Different Sizes of Pipes 


Diameter of Pipe 

Size of Register 

6 in. 

6 X 10 in. 

7 “ 

7 X 10 ‘ 

8 “ 

8 X 12 “ 

9 “ 

9 X 14 “ 

10 “ 

10 X 15 “ 

11 “ 

11 X 16 “ 

12 “ 

12 X 17 “ 

13 “ 

14 X 20 “ 

14 “ 

14 X 22 “ 

15 “ 

15 X 22 “ 

16 “ 

16 X 24 “ 


Combination Systems. A combination system for heating by 
hot air and hot water consists of an ordinary furnace with some form 
of surface for heating water, placed either in contact with the fire or 
suspended above it. Fig. 12 shows a common arrangement where 
part of the heating surface forms a portion of the lining to the firepot 
and the remainder is above the fire. 

Care must be taken to proportion properly the work to be done 
by the air and the water; else one will operate at the expense of the 
other. One square foot of heating surface in contact with the fire is 
capable of supplying from 40 to 50 square feet of radiating surface, 


43 









34 


HEATING AND VENTILATION 



Fig. 12. Combination Furnace, for Heating by Both Hot Air and Hot Water. 

manufacturers and have them proportion the surfaces as their experi¬ 
ence has found best for their particular type of furnace. 

Care and Management of Furnaces. The following general 
rules apply to the management of all hard coal furnaces. 

The fire should be thoroughly shaken once or twice daily in cold 
weather. It is well to keep the firepot heaping full at all times. In 


and one square foot suspended over the fire will supply from 15 to 25 
square feet of radiation. 

The value or efficiency of the heating surface varies so widely in 
different makes that it is best to state the required conditions to the 


44 


















HEATING AND VENTILATION 


35 


this way a more even temperature may be maintained, less attention is 
required, and no more coal is burned than when the pot is only partly 
filled. In mild weather the mistake is frequently made of carrying a 
thin fire, which requires frequent attention and is likely to die out. 
Instead, to diminish the temperature in the house, keep the firepot 
full and allow ashes to accumulate on the grate (not under it) by shak¬ 
ing less frequently or less vigorously. The ashes will hold the heat 
and render it an easy matter to maintain and control the fire. When 
feeding coal on a low fire, open the drafts and neither rake nor shake 
ihe fire till the fresh coal becomes ignited. The air supply to the fire 
is of the greatest importance. An insufficient amount results in incom¬ 
plete combustion and a great loss of heat. To secure proper combus¬ 
tion, the fire should be controlled principally by means of the ash-pit 
through the ash-pit door or slide. 

The smoke-pipe damper should be opened only enough to carry 
off the gas or smoke and to*give the necessary draft. The openings 
in the feed door act as a check on the fire, and should be kept closed 
during cold weather, except just after firing, when with a good draft 
i they may be partly opened to inc rease the air-supply and promote the 
proper combustion of the gases. 

Keep the ash-pit clear to avoid warping or melting the grate. 
The cold-air box should be kept wide open except during winds or 
when the fire is low. At such times it may be partly, but never com¬ 
pletely closed. Too much stress cannot be laid on the importance 
of a sufficient air-supply to the furnace. It costs little if any more 
to maintain a comfortable temperature in the house night and day 
than to allow the rooms to become so cold during the night that the 
fire must be forced in the morning to warm them up to a comfortable 
temperature. 

In case tne warm air fails at times to reach certain rooms, it 
may be forced into them by temporarily closing the registers in other 
rooms. The current once established will generally continue after 
the other registers have been opened. 

It is best to burn as hard coal as the draft will warrant. Egg 
size is better than larger coal, since for a given weight small lumps 
expose more surface and ignite more quickly than larger ones. The 
furnace and smoke-pipe should be thoroughly cleaned once a year. 


45 






36 


HEATING AND VENTILATION 


This should be done just after the fire has been allowed to go out in 
the spring. i | 

STEAM BOILERS 

Types. The boilers used for heating are the same as have already 
been described for power work. In addition there is the cast-iron 
sectional boiler, used almost exclusively for dwelling-houses. 

Tubular Boilers. Tubular boilers are largely used for heating 
purposes, and are adapted to all classes of buildings except dwelling- 
houses and the special cases mentioned later, for which sectional 
boilers are preferable. A boiler horse-power has been defined as the 
evaporation of 34 \ pounds of water from and at a temperature of 212 
degrees, and in doing this 33,317 B. T. U. are absorbed, which are 
again given out when the steam is condensed in the radiators. Hence 
to find the boiler H. P. required for warming any given building, we 
have only to compute the heat loss per hour by the methods already 
given, and divide the result by 33,330. It is more common to divide 
by the number 33,000, which gives a slightly larger boiler and is on 
the side of safety. 

The commercial horse-power of a well-designed boiler is based 
upon its heating surface; and for the best economy in heating work, 
it should be so proportioned as to have about 1 square foot heating of 
surface for each 2 pounds of water to be evaporated from and at 212 
degrees F. This gives 34.5 -t- 2 = 17.2 square feet of heating surface 
per horse-power, which is generally taken as 15 in practice. Makers of 
tubular boilers commonly rate them on a basis of 12 square feet of heat¬ 
ing surface per horse-power. This is a safe figure under the conditions 
of power work, where skilled firemen are employed and where more 
care is taken to keep the heating surfaces free from soot and ashes. 
For heating plants, however, it is better to rate the boilers upon 15 
square feet per horse-power as stated above. 

There is some difference of opinion as to the proper method of 
computing the heating surface of tubular boilers. In general, all 
surface is taken which is exposed to the hot gases on one side and to 
the water on the other. A safe rule, and the one by which Table 
XII is computed, is to take J the area of the shell, *f of the rear head, 
less the tube area, and the interior surface of all the tubes. 

The required amount of grate area, and the proper ratio of heat- 


46 











HEATING AND VENTILATION 


37 


ing surface to grate area, vary a good deal, depending on the character 
of the fuel and on the chimney draft. By assuming the probable 
rates of combustion and evaporation, we may compute the required 
grate area for any boiler from the formula: 

„ H.P.X 34.5 
* “ E XC 

in which 


£ = Total grate area, in square feet; 

E = Pounds of water evaporated per pound of coal; 

C = Pounds of coal burned per square foot of grate per hour. 
Table XI gives the approximate grate area per H. P. for different 
rates of evaporation and combustion as computed by the above 
equation. 

TABLE XI 


Orate Area per Horse=Power for Different Rates of Evaporation and 

Combustion 


Pounds of Coal Burned per Square Foot of Grate per Hour 


Pounds of Steam per 
Pound of Coal 

8 lbs. 

lO lbs. 

12 lbs. 

Square Feet of Grate Surface per Horse-Power 

10 

.43 

.35 

.28 

9 

.48 

.38 

.32 

8 

.54 

.43 

.36 

7 

.62 

.49 

.41 

6 

.72 

.58 

.48 


For example, with an evaporation of 8 pounds of steam per pound of 
soal, and a combustion of 10 pounds of coal per square foot of grate, .43 of a 
square foot of grate surface per H. P. would be called for. 


The ratio of heating to grate surface in this type of boiler ranges 
'rom 30 to 40, and therefore allows under ordinary conditions a com¬ 
bustion of from 8 to 10 pounds of coal per square foot of grate. This 
s easily obtained with a good chimney draft and careful firing. The 
arger the boiler, the more important the plant usually, and the greater 
he care bestowed upon it, so that we may generally count on a higher 
■ate of combustion and a greater efficiency as the size of the boiler 
ncreases. Table XII will be found very useful in determining 
he size of boiler required under different conditions. The grate 
, re a is computed for an evaporation of 8 pounds of water per pound 


47 































JM 1 Pj XV 

Shell 

Inches 

30 

36 

42 

48 

54 

60 

66 

72 


HEATING AND VENTILATION 


TABLE XII 


Number 
of Tubes 

Diameter 
of Tubes 
in Inches 

Length 
of Tubes 
in Feet 

Horse- 

Power 

Size of 
Grate in 
Inches 

Size of 

U PTAKE 
in Inches 

28 

2^ 

6 

8.5 

24 

X 

36 

10x14 


7 

9.9 

24 

X 

36 

10 x 14 



8 

11.2 

24 

X 

36 

10 x 14 



9 

12.6 

24 

X 

42 

10 x 14 



10 

14.0 

24 

X 

42 

10 x 14 

34 

2^ 

8 

13.6 

30 

X 

36 

10x16 


9 

15.3 

30 

X 

42 

10 x 18 



10 

16.9 

30 

X 

42 

10 x 18 



11 

18.6 

30 

X 

48 

10 x 20 



12* 

20.9 

30 

X 

48 

10x20 

34 

3 

9 

18.5 

36 

X 

42 

10 x 20 



10 

20.5 

36 

X 

42 

10 x20 



11 

22.5 

36 

X 

48 

10 x 25 



12 

24.5 

36 

X 

48 

10 x25 



13 

26.5 

36 

X 

48 

10 x28 



14 

28.5 

36 

X 

54 

10x28 

44 

3 

10 

30.4 

42 

X 

48 

10x28 



11 

33.2 

42 

X 

48 

10x28 



12 

35.7 

42 

X 

54 

10 x 32 



13 

38.3 

42 

X 

54 

10 x32 



14 

40.8 

42 

X 

60 

10 x36 



15 

43.4 

42 

X 

60 

10 x36 



16 

45.9 

42 

X 

60 

10 x36 

54 

3 

11 

34.6 

48 

X 

54 

10x38 



12 

37.7 

48 

X 

54 

10 x 38 



13 

40.8 

48 

X 

54 

10 x38 



14 

43.9 

48 

X 

54 

10 x 38 



15 

47.0 

48 

X 

60 

10 x40 



16 

50.1 

48 

X 

60 

10x40 

46 

zy 2 

17 

53.0 

48 

X 

60 

10x40 

72 

3 

12 

48.4 

54 

X 

60 

12 x40 



13 

52.4 

54 

X 

60 

12 x40 



14 

56.4 

54 

X 

60 

12x40 



15 

60.4 

54 

X 

66 

12x42 



16 

64.4 

54 

X 

66 

12x42 

64 

3/ ^ 

17 

71.4 

54 

X 

72 

12x48 


18 

75.6 

54 

X 

72 

12x48 

90 

3 

14 

70.1 

60 

X 

66 

12x48 



15 

75.0 

60 

X 

72 

12x52 



16 

80.0 

60 

X 

72 

12 x 52 

78 

3 M 

17 

86.0 

60 

X 

78 

12 x56 


18 

91.1 

60 

X 

78 

12x56 



19 

96.2 

60 

X 

78 

12 x56 

62 

4 

20 

93.1 

60 

X 

78 

12x56 

114 

3 

14 

87.4 

66 

X 

72 

12 x 56 



15 

93.6 

66 

X 

72 

12 x56 



16 

99.7 

66 

X 

78 

12 x 62 

98 

3^ 

17 

106.4 

66 

X 

78 

12 x62 


18 

112.6 

66 

X 

84 

12 x66 



19 

118.8 

66 

X 

84 

12 x66 

72 

4 

20 

107.3 

66 

X 

84 

12x66 


48 


Size op 
Smoke- 
pipe in 
Sq. In- 


200 

200 

200 

280 

280 

280 

280 

320 

320 

360 

360 

360 

380 

380 

380 

380 

400 

400 

460 

460 

460 

500 

500 

550 







































HEATING AND VENTILATION 


39 


of coal, which corresponds to an efficiency of about 60 per cent, and 
is about the average obtained in practice for heating boilers. 

The areas of uptake and smoke-pipe are figured on a basis of 
1 square foot to 7 square feet of grate surface, and the results given 
m round numbers. In the smaller sizes the relative size of smoke- 
pipe is greater. The rate of combustion runs from 6 pounds in the 
smaller sizes to 11J in the larger. Boilers of the proportions given 
in the table, correspond well with those used in actual practice, and 
may be relied upon to give good results under all ordinary conditions. 

Water-tube boilers are often used for heating purposes, but more 
especially in connection with power plants. The method of com¬ 
puting the required H. P. is the same as for tubular boilers. 

Sectional Boilers. Fig. 13 shows a common form of cast-iron 
boiler. It is made up of slabs or sections, each one of which is con¬ 
nected by nipples with headers at the sides and top. The top header 
acts as a steam drum, and the lower ones act as mud drums; they also 
receive the water of condensation from the radiators. The gases 
from the fire pass backward and forward through flues and are finally 
taken off at the rear of the boiler. 

Another common form of sectional boiler is shown in Fig. 14. 
It is made up of sections which increase the length like the one just 
described. These boilers have no drum connecting with the sections; 
but instead, each section connects with the adjacent one through 
openings at the top and bottom, as shown. 

The ratio of heating to grate surface in boilers of this type ranges 
from 15 to 25 in the best makes. They are provided with the usual 
attachments, such as pressure-gauge, water-glass, gauge-cocks, and 
safety-valve; a low-pressure damper regulator is furnished for operat¬ 
ing the draft doors, thus keeping the steam pressure practically con¬ 
stant. A pressure of from 1 to 5 pounds is usually carried on these 
boilers, depending upon the outside temperature. The usual setting 
is simply a covering of some kind of non-conducting material like 
plastic magnesia or asbestos, although some forms are enclosed in 
light brickwork. 

In computing the required size, we may proceed in the same 
manner as in the case of a furnace. For the best types of house¬ 
heating boilers, we may assume a combustion of 5 pounds of coal per 
square foot of grate per hour, and an average efficiency of 60 per cent, 


49 


40 


HEATING AND VENTILATION 


which corresponds to 8,000 B. T. U. per pound of coal, available for 
useful work. 

In the case of direct-steam heating, we have only to supply heat 
to offset that lost by radiation and conduction; so that the grate area 
may be found by dividing the computed heat loss per hour by 8,000, 
which gives the number of pounds of coal; and this in turn, divided 
by 5, will give the area of grate required. The most efficient rate of 



combustion will depend somewhat upon the ratio between the grate 
and heating surface. It has been found by experience that about J 
of a pound of coal per hour for each square foot of heating surface 
gives the best results; so that, by knowing the ratio of heating surface 
to grate area for any make of heater, we can easily compute the most 
efficient rate of combustion, and from it determine the necessary grate 
area. 


50 
































































HEATING AND VENTILATION 


41 



For example, suppose the heat loss from a building to be 480,000 
B. T. U. per hour, and that we wish to use a heater in which the ratio 
of heating surface to grate area is 24. What will be the most efficient 
rate of combustion and 
the required grate area? 

480,000 -f 8,000 = 60 
pounds of coal per hour, 
and 24-r-4 = 6, which is 
the best rate of combus¬ 
tion to employ; there¬ 
fore 60 -T- 6 = 10, the grate 
area required. 

There are many dif 
ferent designs of cast- 
iron boilers for low-pres¬ 
sure steam and hot-water 
heating. In general, 
boilers having a drum 
connected by nipples 
with each section give dryer steam and hold a steadier water¬ 
line than the second form, especially when forced above their 
normal capacity. The steam, in passing through the openings 
between successive sections in order to reach the outlet, is apt to 
carry with it more or less water, and to choke the openings, thus 
producing an uneven pressure in different parts of the boiler. 

In the case of hot-water boilers this objection disappears. 

For steam work the opening between the sections should be of good 
size, with an ample steam space above the water-line; and the nozzles 
for the discharge of steam should be located at frequent intervals. 


Fig. 14. Ideal Sectional 36-Inch Steam Boiler. 
Courtesy of American Radiator Company. 


EXAMPLES FOR PRACTICE 

1. The heat loss from a building is 240,000 B. T. U. per hour, 

and the ratio of heating to grate area in the heater to be used is 20. 
What will be the required grate area? Ans. 6 sq. ft. 

2. The heat loss from a building is 168,000 B. T. U. per hour, 
and the chimney draft is such that not over 3 pounds of coal per hour 
can be burned per square foot of grate. What ratio of heating to 
grate area will be necessary, and what will be the required grate area? 

Ans. Ratio, 12. Grate area, 7 sq. ft. 


51 



42 


HEATING AND VENTILATION 


Cast-iron sectional boilers are used for dwelling-houses, small 
schoolhouses, churches, etc., where low pressures are carried. They 
are increased in size by adding more slabs or sections. After a certain 
length is reached, the rear sections become less and less efficient, thus 
limiting the size and power. 

Horse=Power for Ventilation. We already know that one 
B. T. U. will raise the temperature of 1 cubic foot of air 55 degrees, 


_5_5_ 

- l'OOJ 


or -V 0 / 


therefore, to raise 100 cubic feet 1 degree, it will take 1 
B. T. U.; and to raise 100 cubic feet through 100 degrees, it will take 
x 100 B. T. U. In other words, the B. T. U. required to raise 
any given volume of air through any number of degrees in tempera¬ 
ture, is equal to 

Volume of air in cubic ft. X Degrees raised 


55 


55 


• = 127,272 + 


or it will raise 100 cubic feet of 55 degrees, or T W of 1 degree; 


Example. How many B. T. U. are required to raise 100,000 
cubic feet of air 70 degrees? 

100,000 X 70 


To compute the H. P. required for the ventilation of a building, 
we multiply the total air-supply, in cubic feet per hour, by the number 
of degrees through which it is to be raised, and divide the result by 55, 
This gives the B. T. U. per hour, which, divided by 33,000, will give 
the H. P. required. In using this rule, always take the air-supply in 
cubic feet per hour. 

EXAMPLES FOR PRACTICE 

1. The heat loss from a building is 1,650,000 B. T. U. per hour. 
There is to be an air-supply of 1,500,000 cubic feet per hour, raised 
through 70 degrees. What is the total boiler H. P. required? 

Ans. 108. 

2. A high school has 10 classrooms, each occupied by 50 pupils. 

Air is to be delivered to the rooms at a temperature of 70 degrees. 
What will be the total H. P. required to heat and ventilate the building 
when it is 10 degrees below zero, if the heat loss through walls and 
windows is 1,320,000 B. T. U. per hour? Ans. 106+. 


DIRECT=STEAM HEATING 

A system of direct-steam heating consists (1) of a furnace and 












HEATING AND VENTILATION 


43 


boiler for the combustion of fuel and the generation of steam: (2) a 
system of pipes for conveying the steam to the radiators and for 
returning the water of condensation to the boiler; and (3) radiators 
or coils placed in the rooms for diffusing the heat. 

Various types of boilers are used, depending upon the size and 
kind of building to be warmed. Some form of cast-iron sectional 
boiler is commonly used for dwelling-houses, while the tubular or 
water-tiibe boiler is more usually employed in larger buildings. 
Where the boiler is used for heating purposes only, a low steam-pres¬ 
sure of from 2 to 10 pounds is carried, and the condensation flows 
back by gravity to the boiler, which is placed below the lowest radi¬ 
ator. When, for any reason, a higher pres¬ 
sure is required, the steam for the heating 
system is made to pass through a reducing 
valve, and the condensation is returned to 
the boiler by means of a pump or return trap. 

Types of Radiating Surface. The radi¬ 
ation used in direct-steam heating is made 
up of cast-iron radiators of various forms, 
of pipe radiators, and of circulation coils. 

Cast=lron Radiators. The general form 
of a cast-iron sectional radiator is shown in 
Fig. 15. Radiators of this type are made 
up of sections, the number depending upon 
the amount of heating surface required. 

Fig. 16 shows an intermediate section of a 
radiator of this type. It is simply a loop 
with inlet and outlet at the bottom. The 
end sections are the same, except that they 
have legs, as shown in Fig. 17. These sections are connected at 
the bottom by special nipples, so that steam entering at the end 
fills the bottom of the radiator, and, being lighter than the air, rises 
through the loops and forces the air downward and toward the farther 
end, where it is discharged through an air-valve placed about midway 
of the last section. For one-pipe steam work the supply-leg section 
is constructed with low-drip hub, and for two-pipe steam work, the 
return-leg section is constructed with low-drip hub. 

There are many designs varying in height and width, to 



Courtesy of American Radiator 
Company, Chicago. 


53 














44 


HEATING AND VENTILATION 


suit all conditions. The wall pattern shown in Fig. 18 is very con¬ 
venient when it is desired to place the radiator above the floor, as in 

bathrooms, etc.; it is also a con¬ 
venient form to place under the 
windows of halls and churches 
to counteract the effect of cold 
down drafts. It is adapted to 
nearly every place where the or¬ 
dinary direct radiator can be 
used, and may be connected up 
in different ways to meet the va¬ 
rious requirements. 

A low and moderately shallow 
radiator, with ample space for the 
circulation of air between the 
sections, is more efficient than a 
deep radiator with the sections 
closely packed together. One- 
and two-column radiators, so 
called, are preferable to three- 
and four-column, when there is sufficient space to use them. 


V& 


Fig. 16. 




Fig. 17. 


Intermediate and End Sections of Radiator 
Shown in Fig. 15. The end sections 
(at right) have legs. 



Fig. 18. Rococo Wall Radiators. 
Courtesy of American Radiator Company, Chicago. 


The standard height of a radiator is 36 or 38 inches, and, if 
possible, it is better not to exceed this. 


54 
































































HEATING AND VENTILATION 


45 



For small radiators, it is better practice to use lower sections and 
increase the length; this makes the radiator slightly more efficient 
and gives a much better appearance. 

To get the best results from wall radiators, they should be set 
out at least 1J inches from the wall to allow a free circulation of air 
back of them. Patterns having cross-bars should be placed, if 
possible, with the bars in a vertical position, as their efficiency is 
impaired somewhat when placed horizontally. 

Pipe Radiators. This type of radiator (see Fig. 19) is made up of 
wrought-iron pipes 
screwed into a cast- 
iron base. The 
pipes are eithercon- 
nected in pairs at 
the top by return 
bends, or each sep¬ 
arate tube has a 
thin metal dia¬ 
phragm passing up 
the center nearly-to 
the top. It is nec¬ 
essary that a loop 
be formed, else a 
“dead end” would 
occur. This would 
become filled with 
air and prevent 
steam from enter¬ 
ing, thus causing portions of the radiator to remain cold. 

Circulation Coils. These are usually made up of 1 or lj-inch 
wrought-iron pipe, and may be hung on the walls of a room by means 
of hook plates, or suspended overhead on hangers and rolls. 

Fig. 20 shows a common form for schoolhouse and similar work; 
this coil is usually made of lj-inch pipe screwed into headers or 
branch tees at the ends, and is hung on the wall just below the windows. 
This is known as a branch coil. Fig. 21 shows a trombone coil , which 
is commonly used when the pipes cannot turn a corner, and where 
the entire coil must be placed upon one side of the room. Fig. 22 


Fig. 19. Wrought-iron Pipe Radiator. 


55 










46 


HEATING AND VENTILATION 


is called a miter coil, and is used under the same conditions as a trom¬ 
bone coil if there is room for the vertical portion. This form is not 
so pleasing in appearance as either of the other two, and is found only 
in factories or shops, where looks are of minor importance. 



Fig. 20. Common Form of “Branch” Coil for Circulation of Direct Steam. 

Overhead coils are usually of the miter form, laid on the side and j 
suspended about a foot from the ceiling; they are less efficient than 
when placed nearer the floor, as the warm air stays at the ceiling and 
the lower part of the room is likely to remain cold. They dre used 



Fig. 21. “Trombone” Coil. Used where Entire Coil must be Placed on One Side cf Room 

only when wall coils or radiators would be in the way of fixtures, or 
when they would come below the water-line of the boiler if placed 
near the floor. 

When steam is first turned on a coil, it usually passes through a 



portion of the pipes first and heats them while the others remain cold 
and full of air. Therefore the coil must always be made up in such 
a way that each pipe shall have a certain amount of spring and may 
expand independently without bringing undue strains upon the others. 
Circulation coils should incline about 1 inch in 20 feet toward the 


56 






























HEATING AND VENTILATION 


47 


return end in order to secure proper drainage and quietness of opera¬ 
tion. 

Efficiency of Radiators. The efficiency of a radiator—that is, 
the B. T. U. which it gives off per square foot of surface per hour— 
depends upon the difference in temperature between the steam in the 
radiator and the surrounding air, the velocity of the air over the 
radiator, and the quality of the surface, whether smooth or rough. 
In ordinary low-pressure heating, the first condition is practically 
constant; but the second varies somewhat with the pattern of the 
radiator. An open design which allows the air to circulate freely 
over the radiating surfaces, is more efficient than a closed pattern, 
and for this reason a pipe coil is more efficient than a radiator. 

In a large number of tests of cast-iron and pipe radiators, working 
under usual conditions, the heat given off per square foot of surface 
per hour for each degree difference in temperature between the steam 
and surrounding air was found to average about 1.7 B. T. U. The 
temperature of steam at 3 pounds’ pressure is 220 degrees, and 220—70 
= 150, which may be taken as the average difference between the 
temperature of the steam and the air of the room, in ordinary low- 
pressure work. Taking the above results, we have 150 X 1.7 = 255 
B. T. U. as the efficiency of an average cast-iron or pipe radiator. 
This, for convenient use, may be taken as 250. A circulation coil 
made up of pipes from 1 to 2 inches in diameter, will easily give off 
300 B. T. U. under the same conditions; and a cast-iron wall radiator 
with ample space back of it should have an efficiency equal to that 
of a wall coil. While overhead coils have a higher efficiency than 
cast-iron radiators, their position near the ceiling reduces their effec¬ 
tiveness, so that in practice the efficiency should not be taken over 
250 B. T. U. per hour at the most. Tabulating the above we have: 


TABLE XIII 

Efficiency of Radiators, Coils, etc. 


Type of Radiating Surface 

Radiation per Square Foot of Surface 
per Hour 

Cast-Iron Sectional and Pipe Radiators 

250 B. T. U. 

Wall Radiators 

300 

Ceiling Coils 

200 to 250 

Wall Coils 

300 


57 








48 


HEATING AND VENTILATION 


If the radiator is for warming a room which is to be kept at a 
temperature above or below 70 degrees, or if the steam pressure is 
greater than 3 pounds, the radiating surface may be changed in the 
same proportion as the difference in temperature between the steam 
and the air. 

For example, if a room is to be kept at a temperature of 60°, the 
efficiency of the radiator becomes if? X 250 = 267; that is, the 
efficiency varies directly as the difference in temperature between the 
steam and the air of the room. It is not customary to consider this 
unless the steam pressure should be raised to 10 or 15 pounds or the 
temperature of the rooms changed 15 or 20 degrees from the normal. 

From the above it is easy to compute the size of radiator for any 
given room. First compute the heat loss per hour by conduction and 
leakage in the coldest weather; then divide the result by the effi¬ 
ciency of the type of radiator to be used. It is customary to make the 
radiators of such size that they will warm the rooms to 70 degrees in 
the coldest weather. As the low-temperature limit varies a good deal 
in different localities, even in the same State, the lowest temperature 
for which we wish to p/ovide must be settled upon before any calcu¬ 
lations are made. In New England and through the Middle and 
Western States, it is usual to figure on warming a building to 70 
degrees when the outside temperature is from zero to 10 degrees 
below. 

The different makers of radiators publish in their catalogues, 
tables giving the square feet of heating surface for different styles and 
heights, and these can be used in determining the number of sections 
required for all special cases. 

If pipe coils are to be used, it becomes necessary to reduce square ! 
feet of heating surface to linear feet of pipe; this can be done by means 
of the factors given below. 


Square feet of heating surface X 


3 = linear ft. of 1 -in. pipe 

2.3 = “ “ lfin. “ 

2 = “ “ lj-in. “ 


1.6 


2 -in. 


The size of radiator is made only sufficient to keep the room 
warm after it is once heated; and no allowance is made for warming 
up; that is, the heat given off by the radiator is just equal to that lost 
through walls and windows. This condition is offset in two ways— 


58 





HEATING AND VENTILATION 


49 


first > when the room is cold, the difference in temperature between 
the steam and the air of the room is greater, and the radiator is more 
efficient; and second, the radiator is proportioned for the coldest 
weather, so that for a greater part of the time it is larger than neces¬ 
sary. 

EXAMPLES FOR PRACTICE 

1. The heat loss from a room is 25,000 B. T. U. per hour in 
the coldest weather. What size of direct radiator will be required? 

Ans. 100 square feet. 

2. A schoolroom is to be warmed with circulation coils of 1J- 

inch pipe. The heat loss is 30,000 B. T. U. per hour. What length 
of pipe will be required? Ans. 230 linear feet. 

Location of Radiators. Radiators should, if possible, be placed 
in the coldest part of the room, as under windows or near outside 
doors. In living rooms it is often desirable to keep the windows free, 
in which case the radiators may be placed at one side. Circulation 
coils are run along the outside walls of a room under the windows. 
Sometimes the position of the radiators is decided by the necessary 
location of the pipe risers, so that a certain amount of judgment must 
be used in each special case as to the best arrangement to suit all 
requirements. 

Systems of Piping. There are three distinct systems of piping, 
known as the two-pipe system, the one-pipe relief system, and the one- 
pipe circuit system, with various modifications of each and combina¬ 
tions of the different systems. 

Fig. 23 shows the arrangement of piping and radiators in the 
two-pipe system. The steam main leads from the top of the boiler, 
and the branches are carried along near the basement ceiling. Risers 
are taken from the supply branches, and carried up to the radiators 
on the different floors; and return pipes are brought down to the 
return mains, which should be placed near the basement floor below 
the water-line of the boiler. Where the building is more than two 
stories high, radiators in similar positions on different floors are con¬ 
nected with the same riser, which may run to. the highest floor; and a 
corresponding return drop connecting with each radiator is carried 
down beside the riser to the basement. A system in which the main 
horizontal returns are below the water-line of the boiler is said to 


59 



50 


HEATING AND VENTILATION 


have a wet or sealed return. If the returns are overhead and above the 
water-line, it is called a dry return. Where the steam is exposed to 
extended surfaces of water, as in overhead returns, where the con¬ 
densation partially fills the pipes, there is likely to be cracking or 
water-hammer , due to the sudden condensation of the steam as it 
comes in contact with the cooler water. This is especially noticeable 
when steam is first turned into cold pipes and radiators, and the con¬ 
densation is excessive. When dry returns are used, the pipes should ! 
be large and have a good pitch toward the boiler. 

In the case of sealed returns, the only contact between the steam 



Fig. 23. Arrangement of Piping and Radiators in “Two-Pipe” System. 


and standing water is in the vertical returns, where the exposed sur¬ 
faces are very small (being equal to the sectional area of the pipes), 
and trouble from water-hammer is practically done away with. Dry 
returns should be given an incline of at least 1 inch in 10 feet, while 
for wet returns 1 inch in 20 or even 40 feet is ample. The ends of all 
steam mains and branches should be dripped into the returns. If the 
return is sealed, the drip may be directly connected as shown in Fig. 
24; but if it is dry, the connection should be provided with a siphon 
loop as indicated in Fig. 25. The loop becomes filled with water, 
and prevents steam from flowing directly into the return. As the 


60 























































HEATING AND VENTILATION 


51 


Wat. 


Return 


Line 


& 


Fig. 24. Drip from Steam Main Connected Directly 
to Sealed Return. 


condensation collects in the loop, it overflows into the return pipe and 
is carried away. The return pipes in this case are of course filled with 
steam above the water; but it is steam which has passed through 
the radiators and their return connections, and is therefore at a 
slightly lower pressure; 

L ,_ Steam Maim _ 

so that, if steam were ad- r y 

mitted directly from the 
main, it would tend to 
hold back the water in 
more distant returns and 
cause surging and crack¬ 
ing in the pipes. Some¬ 
times the boiler is at a 
lower level than the basement in which the returns are run, and it then 
becomes necessary to establish a false water-line. This is done by 
making connections as shown in Fig. 26. 

It is readily seen that the return water, in order to reach the 
boiler, must flow through the trap, which raises the water-line or 
seal to the level shown by the dotted line. The balance pipe is to 
equalize the pressure above and below the water in the trap, and 
prevent siphonic action, which would tend to drain the water out of 
the return mains after a flow was once started. 

The balance pipe, when possible, should be 15 or 20 feet in 
length, with a throttle-valve placed near its connection with the 

main. This valve 
should be opened just 
enough to allow the 
steam-pressure to act 
upon the air which oc¬ 
cupies the space above 
the water in the trap; 
but it should not be 
opened sufficiently to 
allow the steam to 
enter in large volume and drive the air out. The success of this 
arrangement depends upon keeping a layer or cushion of cool air 
next to the surface of the water in the trap, and this is easily done 
by following the method here described. 



Fig. 25. Use of Siphon in Connecting Drip from Steam 
Main to a “Dry” Return. 


61 



















52 


HEATING AND VENTILATION 




One=Pipe Relief System. In this system of piping, the radiators 
have but a single connection, the steam flowing in and the condensa¬ 
tion draining out through the same pipe. Fig. 27 shows the method 
of running the pipes for this system. The steam main, as before, 
leads from the top of the boiler, and is carried to as high a point as the 
basement ceiling will allow; it then slopes downward with a grade 
of about 1 inch in 10 feet, and makes a circuit of the building or a 
portion of it. 

Risers are taken from the top and carried to the radiators above, 
as in the two-pipe system; but in this case, the.condensation flows 
back through the same pipe, and drains into the return main near the 

floor through 



drip connections 
which are made 
at frequent in¬ 
tervals. In a 
two-story build¬ 
ing, the bottom 
of each riser to 
the second floor 
is dripped; and 
in larger build¬ 
ings, it is cus¬ 
tomary to drip 
each riser that 
has more than 
one radiator con¬ 


nected with it. If the radiators are large and at a considerable dis¬ 
tance from the next riser, it is better to make a drip connection for 
each radiator. When the return main is overhead, the risers should 
be dripped through siphon loops; but the ends of the branches 
should make direct connection with the returns. This is the reverse 
of the two-pipe system. In this case the lowest pressure is at the 
ends of the mains, so that steam introduced into the returns at these 
points will cause no trouble in the pipes connecting between these and 
the boiler. 

If no steam is allowed to enter the returns, a vacuunj will be 
formed, and there will be no pressure to force the water back to the 


62 





























HEATING AND VENTILATION 53 

boiler. A check-valve should always be placed in the main return 


Fig. 28. Arrangement of Piping and Radiators in “One-Pipe Circuit” System. 

There is but little difference in the cost of the two systems, as 
larger pipes and valves are required for the single-pipe method 


Fig. 27. Arrangement of Piping and Radiators in “One-Pipe Relief” System. 

near the boiler, to prevent the water from flowing out in case of a 
vacuum being formed suddenly in the pipes. 


63 






















































































54 


HEATING AND VENTILATION 




With radiators of medium size and properly proportioned connections, 
the single-pipe system in preferable, there being but one valve to 
operate and only one-half the number of risers passing through the 
lower rooms. 

One=Pipe Circuit System. In this case, illustrated in Fig. 28, the 
steam main rises to the highest point of the basement, as before; and 
then, with a considerable pitch, makes an entire circuit of the build¬ 
ing, and again connects with the boiler below the water-line. Single 

risers are taken 



from the top; and 
the condensa¬ 
tion drains back 
t h r o u g h the 
same pipes, and 
is carried along 
with the flow of 
steam to the ex¬ 
treme end of the 
main, where it is 
returned to the 
boiler. The 
main is made 
large, and of 
the same size 


throughout its entire length. It must be given a good pitch to insure 
satisfactory results. 

One objection to a single-pipe system is that the steam and return 
water are flowing in opposite directions, and the risers must be made 
of extra large size to prevent any interference. This is overcome in 
large buildings by carrying a single riser to the attic, large enough 
to supply the entire building; then branching and running “drops”’ 
to the basement. In this system the flow of steam is downward, as 
well as that of water. This method of piping may be used with good 
results in two-pipe systems as well. Care must always be taken that 
no pockets or low points occur in any of the lines of pipe; but if for 
any reason they cannot be avoided, they should be carefully drained. 

A modification of this system, adapting it to large buildings, is 
shown in diagram in Fig. 29. The riser shown in this case is one of 





































HEATING AND VENTILATION 


55 


, several, the number depending upon the size of the building; and 
may be supplied at either bottom or top as most desirable. If steam 
is supplied at the bottom of the riser, as shown in the cut, all of the 
drip connections with the return drop, except the upper one, should 



be sealed with either a siphon loop or a check-valve, to prevent the 
steam from short-circuiting and holding back the condensation in the 
returns above. If an overhead supply is used, the arrangement 
should be the reverse; that is, all return connections should be sealed 
except the lowest. 

Sometimes a separate drip is carried down from each set of 
radiators, as shown on the lower story, being connected with the 
main return below the water-line of the 
boiler. In case this is done, it is well to 
provide a check-valve in each drip below 
the water-line. 

In buildings of any considerable size, 
it is well to divide the piping system into 
sections by means of valves placed in the 
corresponding supply and return branches. 

These are for use in case of a break in 
any part of the system, so that it will be 
necessary to shut off only a small part of 
the heating system during repairs. In tall buildings, it is customary 
to place valves at the top and bottom of each riser, for the same 
purpose. 

Radiator Connections. Figs. 30, 31, and 32 show the common 



65 






































































































56 


HEATING AND VENTILATION 


methods of making connections between supply pipes and radiators. 
Fig. 30 shows a two-pipe connection with a riser; the return is carried 
down to the main below. Fig. 31 shows a single-pipe connection 
with a basement main; and Fig. 32, a single connection with a riser. 

Care must always be taken to make the horizontal part of the 
piping between the radiator and riser as short as possible, and to give 
it a good pitch toward the riser. There are various ways of making 
these connections, especially suited to different conditions; but the 
examples given serve to show the general principle to be followed. 

Figs. 20, 21, and 22 show the common methods of making steam 
and return connections with circulation coils. The position of the 
air-valve is shown in each case. 

Expansion of Pipes. Cold steam pipes expand approximately 






Fig. 33. Elevation and Plan of Swivel-Joint to Counteract Effects of Expansion and 
Contraction in Pipes. 

1 inch in each 100 feet in length when low-pressure steam is turned 
into them; so that, in laying out a system of piping, we must arrange 
it in such a manner that there will be sufficient “spring” or “give” to 
the pipes to prevent injurious strains. This is done by means of off¬ 
sets and bends. In the case of larger pipes this simple method will 
not be sufficient, and swivel or slip joints must be used to take up the 
expansion. 

The method of making up a swivel-joint is shown in Fig. 33. 
Any lengthening of the pipe A will be taken up by slight turning or 
swivel movements at the points B and C. A slip-joint is shown in 


66 































HEATING AND VENTILATION 


57 



Fig. 34. The part c slides inside the shell d, and is made steam- 
tight by a stuffing-box, as shown. The pipes are connected at the 
flanges^. and B. 

When pipes 
pass through 
floors or parti¬ 
tions, the wood¬ 
work should be 
protected by gal- 
vanized-iron 
sleeves having a 

diameter from j to 1 inch greater than the pipe. Fig. 35 shows a 

form of adjustable floor-sleeve 
which may be lengthened or 
shortened to conform to the 
thickness of floor or partition. 
If plain sleeves are used, a 
plate should be placed around 


Fig. 34. 


‘Slip-Joint” Connection to Take Care of Expansion 
and Contraction of Pipes. 




Fig. 36. Floor-Plate Adjusted to Plain 
Sleeve for Carrying Pipe through 
Floor or Partition. 


Fig. 35. Ad 3 UStaDie Metal &ieeve ior carrying — * ~ ££ rt ifion 

Pipe through Floor or Partition. Floor or Partition. 

the pipe where it passes through the floor or partition. The 





Fig. 37. Angle Valve. 


Fig. 38. Offset Valve. 
Valves for Radiator Connections. 


Fig. 39. Corner Valve. 


made in two parts so that they may be put in place after the pipe is 
hung. A plate of this kind is shown in Fig. 36. 


67 






















































































58 


HEATING AND VENTILATION 


Valves* The different styles commonly used for radiator con¬ 
nections are shown in Figs. 37,38, and 39, and are known as angle , 
offset , and corner valves, respectively. The first is used when the 
radiator is at the top of a riser or when the connections are like those 
shown in Figs. 30, 31, and 32; the second is used when the connection 



between the riser and radiator is above the floor; and the third, when 
the radiator has to be set close in the corner of a room and there is not 
space for the usual connection. 

A globe valve should never be used in a horizontal steam supply 
or dry return. The reason for this is plainly 
shown in Fig. 40. In order for water to flow 
through the valve, it must rise to a height 
shown by the dotted line, which would half 
fill the pipes, and cause serious trouble from 
water-hammer. The gate valve shown in 
Fig. 41 does not have this undesirable fea¬ 
ture, as the opening is on a level with the 
bottom of the pipe. 


Fig. 42. Simplest Form of Air-Valve. Operated by Hand. 

Air=Valves. Valves of various kinds are used for freeing the 
radiators from air when steam is turned on. Fig. 42 shows the 
simplest form, which is operated by hand. Fig. 43 is a type of auto¬ 
matic valve, consisting of a shell, which is attached to the radiator. 
F is a small opening which may be closed by the spindle C, which 



C" ) 



Fig. 41. Gate Valve. 


68 




















































HEATING AND VENTILATION 


59 


is provided with a conical end. D is a strip composed of a layer of 
iron or steel and one of brass soldered or brazed together. The 
action of the valve is as follows: 
when the radiator is cold and filled 
with air the valve stands as shown 
in the cut. When steam is turned 
on, the air is driven out through 
the opening B. As soon as this 
is expelled and steam strikes the 
strip D , the two prongs spring 
apart owing to the unequal ex¬ 
pansion of the two metals due to 
the heat of the steam. This 
raises the spindle C, and closes 
the opening so that no steam can 
escape. If air should collect in 
the valve, and the metal strip 
become cool, it would contract, 
and the spindle would drop and 
allow the air to escape through B 

as before. E is an adjusting nut. F is a float attached to the spindle, 
and is supposed, in case of a sudden rush 
of water with the air, to rise and close the 
opening; this action, however, is some¬ 
what uncertain, especially if the pressure 
of water continues for some time. 

There are other types of valves acting 
on the same principle The valve shown 




c 



$ j§JJ 





Fig. 44. Section of Jenkins Im¬ 
proved Automatic Air-Valve. 


Fig. 45. Automatic Air-Valve. 
Operated by Expansion of 
Drum CDue to Vaporiza¬ 
tion of Alcohol with 
which it is Partly 
Filled. 


in Fig. 44 is closed by the expansion of a piece of vulcanite instead 
cf a metal strip, and has no water float. 


69 



















































60 


HEATING AND VENTILATION 


The valve shown in Fig. 45 acts on a somewhat different prin¬ 
ciple. The float C is made of thin brass, closed at top and bottom, 
and is partially filled with wood alcohol. When steam strikes the 
float, the alcohol is vaporized, and creates a pressure sufficient to 
bulge out the ends slightly, which raises the spindle and closes the 
opening B. 

Fig. 46 shows a form o‘f so-called vacuum valve. It acts in a 
similar manner to those already described, but has in addition a 
ball check which prevents the air from being 
drawn into the radiator, should the steam go 
down and a vacuum be formed. If a partial 
vacuum exists in the boiler and radiators, the 
boiling point, and consequently the tempera¬ 
ture of the steam, are lowered, and less heat is 
given off by the radiators. This method of 
operating a heating plant is sometimes advo¬ 
cated for spring and fall, when little heat is re¬ 
quired, and when steam under pressure would 
overheat the rooms. 

Pipe Sizes. The proportioning of the steam 
pipes in a heating plant is of the greatest im¬ 
portance, and should be carefully worked out 
by methods which experience has proved to be 
correct. There are several ways of doing this; 
but for ordinary conditions, Tables XIV, XV, 
and XVI have given excellent results in actual practice. They 
have been computed from what is known as D’Arcy’s formula, with 
suitable corrections made for actual working conditions. As the 
computations are somewhat complicated, only the results will be given 
here, with full directions for their proper use. 

Table XIV gives the flow of steam in pounds per minute for 
pipes of different diameters and with varying drops in pressure be¬ 
tween the supply and discharge ends of the pipe. These quantities 
are for pipes 100 feet in length; for other lengths the results must be 
corrected by the factors given in Table XVI. As the length of pipe 
increases, friction becomes greater, and the quantity of steam dis¬ 
charged in a given time is diminished. 

Table XIV is computed on the assumption that the drop in 



Fig. 46. Vacuum Valve. 


70 















HEATING AND VENTILATION 


61 


TABLE XIV 


Flow of Steam in Pipes of Various Sizes, with Various Drops in Pres¬ 
sure between Supply and Discharge Ends 

Calculated for 100-Foot Lengths of Pipe 


Drop in Pressure (Pounds) 


A 

X 

3^ 

X 

1 

ix 

2 

3 

4 

5 

1 

.44 

.63 

.78 

91 

1.13 

1.31 

1.66 

1.97 

2.26 

ix 

.81 

1.16 

1.43 

1.66 

2.05 

2.39 

3.02 

3.59 

4.12 

i X 

1.06 

1.89 

2.34 

2.71 

3.36 

3.92 

4.94 

5.88 

6.75 

2 

2.93 

4.17 

5.16 

5.99 

7.43 

8.65 

10.9 

13.0 

14.9 

2^ 

5.29 

7.52 

9.32 

10.8 

13.4 

15.6 

19.7 

23.4 

26.9 

3 

8.61 

12.3 

15.2 

17.6 

21.8 

25.4 

32 

31.8 

43.7 

3y 2 

12.9 

18.3 

22.6 

26.3 

32.5 

37.9 

47.8 

56.9 

65.3 

4 

18.1 

25.7 

31.8 

36.9 

45.8 

53.3 

67.2 

80.1 

91.9 

5 

32.2 

45.7 

56.6 

65.7 

81.3 

94.7 

120 

142 

163 

6 

51.7 

73.3 

90.9 

106 

131 

152 

192 

229 

262 

7 

76.7 

109 

135 

157 

194 

226 

285 

339 

390 

8 

108 

154 

190 

222 

274 

319 

402 

478 

549 

9 

147 

209 

258 

299 

371 

432 

545 

649 

745 

10 

192 

273 

339 

393 

487 

567 

715 

852 

977 

12 

305 

434 

537 

623 

771 

899 

1,130 

1,350 

1,550 

15 

535 

761 

942 

1,090 

1,350 

1,580 

1,990 

2,370 

2,720 


pressure between the two ends of the pipe equals the initial pressure. 
If the drop in pressure is less than the initial pressure, the actual 
discharge will be slightly greater than the quantities given in the table; 

TABLE XV 

Factors for Calculating Flow of Steam in Pipes under Initial Pres¬ 
sures above Five Pounds 

To be used in connection with Table XIV 


Drop in 
Pressure 


Initial Pressure (Pounds) 


in Pounds 

10 

20 

30 

40 

60 

80 

i 

i 

1 

1.27 

1.49 

1.68 

1.84 

2.13 

2.38 

1.26 

1.48 

1.66 

1.83 

2.11 

2.36 

1.24 

1.46 

1.64 

1.80 

2.08 

2.32 

2 

1.21 

1.41 

1.59 

1.75 

2.02 

2.26 

3 

1.17 

1.37 

1.55 

1.70 

1 .97 

2.20 

4 

1.14 

1.34 

' 1.51 

1.66 

1 .92 

2.14 

5 

1.12 

1.31 

1.47 

1.62 

1.87 

2.09 


but this difference will be small for pressures up to 5 pounds, and may 
be neglected, as it is on the side of safety. For higher initial pressures, 
Table XV has been prepared. This is to be used in connection with 
Table XIV as follows: First find from Table XIV the quantity of 
steam which will be discharged through the given diameter of pipe 


71 








































62 


HEATING AND VENTILATION 


TABLE XVI 

Factors for Calculating Flow of Steam in Pipes of Other Lengths 


than 100 Feet 


! 

hs 


Feet 

Factor 

10 

3.16 

20 

2.24 

30 

1.82 

40 

1.58 

50 

1.41 

60 

1.29 

70 

1.20 

80 

1.12 

90 

1.05 

100 

1.00 

110 

.95 


Feet 

Factor 

120 

.91 

130 

.87 

140 

.84 

150 

.81 

160 

.79 

170 

.76 

180 

.74 

190 

.72 

200 

.70 

225 

.66 

250 

.63 


Feet 

Factor 

Feet 

Factor 

275 

.60 

600 

.40 

300 

.57 

650 

.39 

325 

.55 

700 

.37 

350 

.53 

750 

.36 

375 

.51 

800 

.35 

. 400 

.50 

850 

.34 

425 

.48 

900 

.33 

450 

.47 

950 

.32 

475 

.46 

1,000 

.31 

500 

.45 



550 

.42 




with the assumed drop in pressure; then look in Table XV for the 
factor corresponding with the assumed drop and the higher initial 
pressure to be used. The quantity given in Table XIV, multiplied 
by this factor, will give the actual capacity of the pipe under the given 
conditions. 


Example —What weight of steam will be discharged through a 3-inch 
pipe 100 feet long, with an initial pressure of 60 pounds and a drop of 2 pounds? 

Looking in Table XIV, we find that a 3-inch pipe will dis¬ 
charge 25.4 pounds of steam per minute with a 2-pound drop. Then 
looking in Table XV, we find the factor corresponding to 60 pounds 
initial pressure and a drop of 2 pounds to be 2.02. Then according 
to the rule given, 25.4 X 2.02 = 51.3 pounds, which is the capacity 
of a 3-inch pipe under the assumed conditions. 

Sometimes the problem will be presented in the following way: 
What size of pipe will be required to deliver 80 pounds of steam a 
distance of 100 feet with an initial pressure of 40 pounds and a drop 
of 3 pounds? 

We have seen that the higher the initial pressure with a given 
drop, the greater will be the quantity of steam discharged; therefore 
a smaller pipe will be required to deliver 80 pounds of steam at 40 
pounds than at 3 pounds initial pressure From Table XV, we find 
that a given pipe will discharge 1.7 times as much steam per minute 
with a pressure of 40 pounds and a drop of 3 pounds, as it would with 
a pressure of 3 pounds, dropping to zero. From this it is evident 
that if we divide 80 by 1.7 and look in Table XIV under “3 pounds 


72 




























HEATING AND VENTILATION 


63 


drop” for the result thus obtained, the size of pipe corresponding will 
be that required. Now, 80 -5- 1.7 = 47. The nearest number in the 
table marked “3 pounds drop” is 47.8, which corresponds to a 3J- 
inch pipe, which is the size required. 

These conditions will seldom be met with in low-pressure heating, 
but apply more particularly to combination power and heating plants, 
and will be taken up more fully under that head. For lengths of 
pipe other than 100 feet, multiply the quantities given in Table XIV 
by the factors found in Table XVI. 

Example —What weight of steam will be discharged per minute through 
a 3^-inch pipe 450 feet long, with a pressure of 5 pounds and a drop of £ pound? 

Table XIV, which may be used for all pressures below 10 pounds, 
gives for a 3J-inch pipe 100 feet long, a capacity of 18.3 pounds for 
the above conditions. Looking in Table XVI, we find the correction 
factor for 450 feet to be .47. Then 18.3 X .47 = 8.6 pounds, the 
quantity of steam which will be discharged if the pipe is 450 feet 
long. 

Examples involving the use of Tables XIV, XV, and XVI in 
combination, are quite common in practice. The following example 
will show the method of calculation: 

What size of pipe will be required to deliver 90 pounds of steam per 
minute a distance of 800 feet, with an initial pressure of 80 pounds and a drop 
of 5 pounds? 

Table XVI gives the factor for 800 feet as .35, and Table XV, 
that for 80 pounds pressure and 5 pounds drop, as 2.09. Then 

-—- = 123, which is the equivalent quantity we must look 

. 35 X 2.09 

for in Table XIV. We find that a 4-inch pipe will discharge 91.9 
pounds, and a 5-inch pipe 163 pounds. A 4J-inch pipe is not com¬ 
monly carried in stock, and we should probably use a 5-inch in this 
case, unless it was decided to use a 4-inch and allow a slightly greater 
drop in pressure. In ordinary heating work, with pressures varying 
from 2 to 5 pounds, a drop of j pound in 100 feet has been found to 
give satisfactory results. 

In computing the pipe sizes for a heating system by the above 
methods, it would be a long process to work out the size of each 
branch separately. Accordingly Table XVII has been prepared for 
ready use in low-pressure work. 


73 






64 


HEATING AND VENTILATION 


As most direct heating systems, and especially those in school- 
houses, are made up of both radiators and circulation coils, an effi¬ 
ciency of 300 B. T. U. has been taken for direct radiation of whatever 
variety, no distinction being made between the different kinds. This 
gives a slightly larger pipe than is necessary for cast-iron radiators; 
but it is probably offset by bends in the pipes, and in any case gives a 
slight factor of safety. We find from a steam table that the latent * 
heat of steam at 20 pounds above a vacuum (which corresponds to 
5 pounds’gauge-pressure) is 954 T B.T. U.—which means that, for 
every pound of steam condensed in a radiator, 954 B. T. U. are given 
off for warming the air of the room. If a radiator has an efficiency 
of 300 B. T. U., then each square foot of surface will condense 300 -r- 
954 = .314 pound of steam per hour; so that we may assume in 
round numbers a condensation of J of a pound of steam per hour for 
each square foot of direct radiation, when computing the sizes of 
steam pipes in low-pressure heating. Table XVII has been calculated 
on this assumption, and gives the square feet of heating surface 
TABLE XVII 

Heating Surface Supplied by Pipes of Various Sizes 

Length of Pipe, 100 Feet 


Size of Pipe 

Square Feet of Heating Surface 

1 Pound Drop 

£ Pound Drop 

1 

80 

114 

11 

145 

210 

1* 

190 

340 

2 

525 

750 

2f 

950 

1,350 

3 

1,550 

2,210 

3$ 

2,320 

3,290 

4 

3,250 

4,620 

5 

5,800 

8,220 

6 

9,320 

13,200 

7 

13,800 

19,620 

8 

19,440 

27,720 


which different sizes of pipe will supply, with drops in pressure of 
\ and \ pounds in each 100 feet of pipe. The former should be used 
for pressures from 1 to 5 pounds, and the latter may be used for 
pressures over 5 pounds, under ordinary conditions. The sizes of 
long mains and special pipes of large size should be proportioned 
directly from Tables XIV, XV, and XVI. 


74 












HEATING AND VENTILATION 


65 


Where the two-pipe system is used and the radiators have sepa¬ 
rate supply and return pipes, the risers or vertical pipes may be taken 
from Table XVII; but if the single-pipe system is used, the risers 
must be increased in size, as the steam and water are flowing in oppo¬ 
site directions and must have plenty of room to pass each other. It 
is customary in this case to base the computation on the velocity of 
the steam in the pipes, rather than on the drop in pressure. Assum¬ 
ing, as before, a condensation of one-third of a pound of steam per 
hour per square foot of radiation, Tables XVIII and XIX have been 
prepared for velocities of 10 and 15 feet per second. The sizes given 
in Table XIX have been found sufficient in most cases; but the larger 
sizes, based on a flow of 10 feet per second, give greater safety and 
should be more generally used. The size of the largest riser should 
usually be limited to 2\ inches in school and dwelling-house work, 
unless it is a special pipe carried up in a concealed position. If the 
length of riser is short between the lowest radiator and the main, a 
higher velocity of 20 feet or more may be allowed through this por¬ 
tion, rather than make the pipe excessively large. 


TABLE XV11I TABLE XIX 

Radiating Surface Supplied by Steam Risers 


10 Feet per Second Velocity 

15 Feet per Second Velocity 

Size of Pipe 

Sq. Feet of Radiation 

Size of Pipe 

Sq. Feet of Radiation ' 

1 in. 

30 

1 in. 

50 

H " 

60 

H “ 

90 

H “ 

80 

H “ 

120 

2 “ 

130 

2 “ 

200 

2* “ 

190 

2i “ 

290 

3 “ 

290 

3 “ 

340 

3* “ 

390 

3J “ 

590 


EXAMPLES FOR PRACTICE 

1. How many pounds of steam will be delivered per minute, 

through a 3i-inch pipe 600 feet long, with an initial pressure of 5 
pounds and a drop of \ pound? Ans. 7.32 pounds. 

2. Wh ,t size pipe will be required to deliver 25.52 pounds 
of steam per minute with an initial pressure of 3 pounds and a drop 
of \ pound, the length of the pipe being 50 feet? Ans. 4-inch. 

3. Compute the size of pipe required to supply 10,000 square 
feet cf direct radiation (assume J of a pound of steam per square 


75 


















HEATING AND VENTILATION 


I 

foot per hour) where the distance to the boiler house is 300 feet, and 
the pressure carried is 10 pounds, allowing a drop in pressure of 
4 pounds. Ans. 5-inch (this is slightly larger than is required, while 
a 4-inch is much too small). 

TABLE XX 

Sizes of Returns for Steam Pipes (in Inches) 


Diameter of Steam Pipe 

Diameter of Dry Return 

Diameter of Sealed Return 

1 

1 

f 

H 

1 

1 

14 

n 

1 

2 

H 

'H 

24 

2 

H 

3 

24 

2 

3* 

21 

2 

4 

3 

24 

5 

3 

2i 

6 

34 

3 

7 

3* 

3 

8 

4 

34 

9 

5 

34 

10 

5 

4 

12 

6 

5 


Returns. The size of return pipes is usually a matter of custom 
and judgment rather than computation. It is a common rule among 
steamfitters to make the returns one size smaller than the corre¬ 
sponding steam pipes. This is a good rule for the smaller sizes, but; 
gives a larger return than is necessary for the larger sizes of pipe. 
Table XX gives different sizes of steam pipes with the corresponding 
diameters for dry and sealed returns. 


TABLE XXI 

Pipe Sizes for Radiator Connections 


Square Feet of Radiation 

Steam 

Return 

Two-Pipe 

10 to 30 

30 to 48 

48 to 96 

96 to 150 

f inch 

1 “ 

H “ 

14 “ 

f inch 

i “ 

i “ 

H “ 

Single-Pipe 

10 to 24 

24 to 60 

60 to 80 

80 to 130 

1 Inch 

H “ 

14 “ 

2 “ 



76 

























HEATING AND VENTILATION 


67 


The length of run and number of turns in a return pipe should 
be noted, and any unusual conditions provided for. Where the 
condensation is discharged through a trap into a lower pressure, the 
sizes given may be slightly reduced, especially among the larger 
sizes, depending upon the differences in pressure. 

Radiators are usually tapped for pipe connections as shown in 
Table XXI, and these sizes may be 
used for the connections with the 



Fig 47. Good Position for Shut-Off 
"Valve. 


mains or risers. 

Boiler Connections. The steam 
main should be connected to the 
rear nozzle, if a tubular boiler is 
used, as the boiling of the water is 
less violent at this point and dryer 
steam will be obtained. The shut¬ 
off valve should be placed in such a position that pockets for the 
accumulation of condensation will be avoided. Fig. 47 shows a good 
position for the valve. 

The size of steam connection may be computed by means of the 
methods already given, if desired. But for convenience the sizes 
given in Table XXII may be used with satisfactory results for the 
short runs between the boilers and main header. 

TABLE XXII 

Pipe Sizes from Boiler to Main Header 


Diameter of Boiler 


Size of Steam Pipe 


36 iifches 
42 
48 
54 
60 
66 
72 


3 inches 

4 “ 

4 “ 

5 “ 

5 “ 

6 “ 

6 “ 


The return connection is made through the blow-off pipe, and 
should be arranged so that the boiler can be blown off without draining 
the returns. A check-valve should be placed in the main return, and 
a plug-cock in the blow-off pipe. Fig. 48 shows in plan a good 
arrangement for these connections. 


77 


















68 


HEATING AND VENTILATION 


The feed connections, with the exception of that part exposed 
in the smoke-bonnet, are always made of brass in the best class of 
work. The small section referred to should be of extra heavy wrought 


A/A IN RETURN 


l 



m 

rri 


-M 




TO DRAIN OR 


3 


BLOW-OFF TANK 

Fig. 48. A Good Arrangement of Return and Blow-Off Connections. 


Iron. The branch to each boiler should be provided with a gate 
or globe valve and a check-valve, the former being placed next to the 
boiler. 

Table XXIII gives suitable sizes for return, blow-off, and feed 
pipes for boilers of different diameters. 

TABLE XXIII 

Sizes for Return, Blow-Off, and Feed Pipes 


Diameter 

of Boiler 

Size of Pipe 
for Gravity Return 

Size of Blow-Off 
Pipe 

Size of Feed Pipe 

36 inches 

IT inches 

14 inches 

1 

inch 

42 

it 

2 

“ 

14 

tt 

1 

tt 

48 

tt 

2 

u 

14 

'* 

1 

tt 

54 

tt 

2 4 

u 

2 

u 

H 

tt 

60 

tt 

2* 

tt 

2 

tt 

ii 

tt 

66 

a 

3 

a 

24 

tt 

14 

tt 

72 

tt 

3 

tt 

24 

tt 

14 

tt 


Blow=Oft‘ Tank. Where the blow-off pipe connects with 
sewer, some means must be provided for cooling the water, or the 
expansion and contraction caused by the hot water flowing through 
the drain-pipes will start the joints and cause leaks. For this reason 
it is customary to pass the water through a blow-off tank. A form 
of wrought-iron tank is shown in Fig. 49. It consists of a receiver 
supported on cast-iion cradles. The tank ordinarily stands nearly 
full of cold water. 

The pipe from the boiler enters above the water-line, and the 
sewer connection leads from near the bottom, as shown. A vapor 
pipe is carried from the top of the tank above the roof of the building. 
When water from the boiler is blown into the tank, cold water from 


78 


















































HEATING AND VENTILATION 


@9 


the bottom fiows into the sewer, and the steam is carried off through 
the vapor pipe. The equalizing pipe is to prevent any siphon action 
which might draw the water out of the tank after a flow is once started. 
As only a part of the water is blown out of a boiler at one time, the 
blow-off tank can be of a comparatively .mall size. A tank 24 by 48 
inches should be large enough for boilers up to 48 inches in diameter; 



and one 36 by 72 inches should care for a boiler 72 inches in diameter. 
If smaller quantities of water are blown off at one tijne, smaller tanks 
can be used. The sizes given above are sufficient for batteries of 2 or 
more boilers, as one boiler can be blown off and the water allowed to 
cool before a second one is blown off. Cast-iron tanks are often 
used in place of wrought-iron, and these may be sunk in the ground 
if desired. 


79 

























9 

















































HEATING AND VENTILATION 

PART II 


INDIRECT STEAM HEATING 

As already stated, in the indirect method of steam heating, a 
special form of- heater is placed beneath the floor, and encased in 
galvanized iron or in brickwork. A cold-air box is connected with 
the space beneath the heater; and warm-air pipes at the top are 
connected with registers in the floors or walls as already described for 
furnaces. A separate heater may be provided for each register if the 
rooms are large, or two or mere registers may be connected with the 
same heater if the horizontal runs of pipe are short. Fig. 50 shows 
a section through a heater arranged for introducing hot air into a 
room through a floor register; and Fig. 51 shows the same type of 
heater connected with a wall register. The cold-air box is seen at 
the bottom of the casing; and the air, in passing through the spaces 
between the sections of the heater, becomes warmed, and rises to the 
rooms above. 

Different forms of indirect heaters are shown in Figs. 52 and 53. 
Several sections con¬ 
nected in a single group 
are called a stack. Some¬ 
times the stacks are en¬ 
cased in brickwork built 
up from the basement 
floor, instead of in gal¬ 
vanized iron as shown in 
the cuts. This method 
of heating provides fresh 
air for ventilation, and for 
this reason is especially 
adapted for schoolhouses, hospitals, churches, etc. As com¬ 
pared with furnace heating, it has the advantage of being less 
affected by outside wind-pressure, as long runs of horizontal pipe 



81 













72 


HEATING AND VENTILATION 



are avoided and the heaters can be placed near the registers. In a 
large building where several furnaces would be required, a single 

boiler can be 
used, and the 
number of stacks 
increased to suit 
the existing con¬ 
ditions, thus 
making it neces¬ 
sary to run but 
a single fire. An¬ 
other advantage 
is the large ratio 
between the 
heating and 
grate surface as 
compared with a 

furnace; and as a result, a large quantity of air is warmed to a moder¬ 
ate temperature, in place of a smaller quantity heated to a much 
higher temperature. This gives a more agreeable quality to the air. 
Direct and indirect systems are often combined, in the living rooms, 
hallways and corridors, having only direct radiators for warming. 

Types of Heaters. \ T arious forms of indirect radiators are shown 
in Figs. 52, 53, 54, and 56. A hot-water radiator may be used for 
steam; but a steam radiator cannot always be used for hot water, as 


Fig. 51. Steam Heater Connected to Wall Register- 
Indirect System. 

Courtesy of American Radiator Company, Chicago 



Fig. 52. One Form of Indirect Steam or Hot-Water Heater. 


it must be especially designed to produce a continuous flow of water 
through it from top to bottom. Figs. 54 and 55 show the outside 
and the interior construction of a common pattern of indirect radiator 


82 



HEATING AND VENTILATION 


73 


designed especially for steam. The arrows in Fig. 55 indicate the 
path of the steam through the radiator, which is supplied at the right, 
while the return connection is at the left. The air-valve in this case 
should be connected in the end of the last section near the return. 



Fig. 53. Another Form of Indirect Steam or Hot-Water Heater. 


Avery efficient form of radiator, and one that is especially adapted 
to the warming of large volumes of air, as in schoolhouse work, is 
shown in Fig. 56, and is known as the School 'pin radiator. This can 



Fig. 54. Exterior View of a Common Type of Radiator for Indirect-Steam Heating. 

be used for either steam or hot water, as there is a continuous passage 
downward from the supply connection at the top to the return at the 
bottom. These sections or slabs are made up in stacks after the 



Fig. 55. interior Mechanism of Radiator Shown in Fig. 54. 


manner shown in Fig. 57, which represents an end view of several 
sections connected together with special pipples. 

A very efficient form of indirect heater may be made up of 
wrought-iron pipe joined together with branch tees and return bends. 


83 















































































































74 


HEATING AND VENTILATION 



A heater like that shown in Fig. 58 is known as a box coil. Its effi¬ 
ciency is increased if the pipes are staggered —that is, if the pipes in 
alternate rows are placed over the spaces between those in the row 

below. . t x i 

Efficiency of Heaters. The efficiency of an indirect heater 


Fie 56. “School Pin” Radiator, Especially Adapted for Warming Large Volumes of 
K Air by Either Steam or Hot Wa ter. 


depends upon its form, the difference in temperature between the 
steam and the surrounding air, and the velocity with which the air 
passes over the heater. Under ordinary conditions in dwelling-house 
work, a good form of indirect radiator will give off about 2 B. T. U. 
per square foot per hour for ^_ . — ini n 

BlTiMi 1 

and the entering air. Assum¬ 
ing a steam pressure of 2 
pounds and an outside tem¬ 
perature of zero, we should 
have a difference in tempera¬ 
ture of about 220 degrees, 
which, under the conditions 
stated, would give an efficiency 
of 220 X 2 = 440 B. T. U. 
per hour for each square foot 
of radiation. By making a similar computation for 10 degrees be¬ 
low zero, we find the efficiency to be 460. In the same manner we 
may calculate the efficiency for varying conditions of steam pressure 
and outside temperature. In the case of schoolhouses and similar 
buildings where large volumes of air are warmed to a moderate tem- 



Fig. 57. End View of Several “School Pin” 
Radiator Sections Connected Together. 


84 

























HEATING AND VENTILATION 


75 


perature, a somewhat higher efficiency is obtained, owing to the in¬ 
creased velocity of the air over the heaters. Where efficiencies of 440 
and 460 are used for dwellings, we may substitute 600 and 620 for 
schoolhouses. This corresponds approximately to 2.7 B. T. U. per 
square foot per hour for a difference of 1 degree between the air and 
steam. 

The principles involved in indirect steam heating are similar 
to those already described in furnace heating. Part of the heat given 
off by the radiator must be used in warming up the air-supply to the 
temperature of the room, and part for offsetting the loss by conduction 
through walls and windows.- The method of computing the heating 
surface required, depends upon the volume of air to be supplied to the 
room. In the case of a schoolroom or hall, where the air quantity 



Fig. 58. “Box Coil,” Built Up of Wrought-Iron Pipe, for Indirect-Steam Heating 


is large as compared with the exposed wall and window surface, we 
should proceed as follows: 

First compute the B. T. U. required for loss by conduction 
through walls and windows; and to this, add the B. T. U. required 
for the necessary ventilation; and divide the sum by the efficiency 
of the radiators. An example will make this clear. 

Example. How many square feet of indirect radiation will be required 
to warm and ventilate a schoolroom in zero weather, where the heat loss by 
conduction through walls and windows is 36,000 B. T. U., and the air-supplv 
is 100,000 cubic feet per hour? 

By the methods given under “Heat for Ventilation,” we have 

100,000 X 70 = 127,272 = B. T. U. required for ventilation. 

55 

36 000 + 127,272 = 163,272 B. T. U. = Total heat required. 

This in turn divided by 600 (the efficiency of indirect radiators 
under these conditions) gives 272 square feet of surface required. 


85 


















76 


HEATING AND VENTILATION 


In the case of a dwelling-house the conditions are somewhat 
changed, for a room having a comparatively large exposure will have 
perhaps only 2 or 3 occupants, so that,- if the small air-quantity neces¬ 
sary in this case were used to convey the required amount of heat 
to the room, it would have to be raised to an excessively high temper¬ 
ature. It has been found by experience that the radiating surface 
necessary for indirect heating is about 50 per cent greater than that 
required for direct heating. So for this work we may compute the 
surface required for direct radiation, and multiply the result by 1.5. 

Buildings like hospitals are in a class between dwellings and 
schoolhouses. The air-supply is based on the number of occupants, 
as in schools, but other conditions conform more nearly to dwelling- 
houses. 

To obtain the radiating surface for buildings of this class, we 
compute the total heat required for warming, and ventilation as in 
the case of schoolhouses, and divide the sum by the efficiencies given 
for dwellings—that is, 440 for zero weather, and 460 for 10 degrees 
below. 

Example. A hospital ward requires 50,000 cubic feet of air per hour for 
ventilation; and the heat loss by conduction through walls, etc., is 100,000 
B. T. U. per hour. How many square feet of indirect radiation will be required 
to warm the ward in zero weather? 


50,000 X 70 -f* 55 = 63,636 B. T. U. for ventilation; then, 


63,636 + 100,000 
440 


= 372 + square feet. 


EXAMPLES FOR PRACTICE 

1. A schoolroom having 40 pupils is to be warmed and venti¬ 

lated when it is 10 degrees below zero. If the heat loss by conduction 
is 30,000 B. T. U. per hour, and the air supply is to be 40 cubic feet 
per minute per pupil, how many square feet of indirect radiation will 
be required? Ans. 273. 

2. A contagious ward in a hospital has 10 beds, requiring 6,000 

cubic feet of air each, per hour. The heat loss by conduction in zero 
weather is 80,000 B. T. U. How many square feet of indirect radia¬ 
tion will be required? Ans. 355 

3. The heat loss from a sitting room is 11,250 B. T. U. per 

hour in zero weather. How many square feet of indirect radiation 
will be required to warm it? Ans. 67.5 sq. ft. 








HEATING AND VENTILATION 


77 


Stacks and Casings. It has already been stated that a group of 
sections connected together is called a stack, and examples of these 
with their casings are shown in Figs. 50 and 51. The casings are 
usually made of galvanized iron, and are made up in sections by 
means of small bolts so that they may be taken apart in case it is 
necessary to make repairs. Large stacks are often enclosed in brick¬ 
work, the sides consisting of 8-inch walls, and the top being covered 
over with a layer of brick and mortar supported on light wrought-iron 
tee-bars. Blocks of asbestos are sometimes used for covering, instead 
of brick, the whole being covered over with plastic material of the 
same kind. 

Where a single stack supplies several flues or registers, the 
connections between these and the warm-air chamber are made in 
the same manner as already described for furnace heating. When 
galvanized-iron casings are used, the heater is supported by hangers 
from the floor above. Fig. 

59 shows the method of LAG 
hanging a heater from a screw i. 
wooden floor. If the floor 
is of fireproof construe- / 
tion,the hangers may pass 
up through the brick- Fig « 
work, and the ends be 
provided with nuts and large washers or plates; or they may be clamped 
to the iron beams which carry the floor. Where brick casings are 
used, the heaters are supported upon pieces of pipe or light I-beams 
built into the walls. 

The warm-air Space above the heater should never be less than 
8 inches, while 12 inches is preferable for heaters of large size. The 
cold-air space may be an inch or two less; but if there is plenty of 
room, it is good practice to make it the same as the space above. 

Dampers. The general arrangement of a galvanized-iron casing 
and mixing damper is shown in Fig. 60. The cold-air duct is brought 
along the basement ceiling from the inlet window, and connects 
with the cold-air chamber beneath the heater. The entering air passes 
up between the sections, and rises through the register above, as shown 
by the arrows. When the mixing damper is in its lowest position, 
all air reaching the register must pass through the heater; but if the 



WROT IRON PIPE 

>. Method of Hanging a Heater below a Wooden 
Floor. 


87 































78 


HEATING AND VENTILATION 


damper is raised to the position shown, part of the air will pass by 
without going through the heater, and the mixture entering through 
the register will be at a lower temperature than before. By changing 


FLOOR REG/STFR 



GALVAN/ZED IRON SLIDING DOOR 
CASING 

Fig. 60. General Arrangement of a Galvanized-Iron Casing and Mixing Damper 
Damper between Heater and Register. 

the position of the damper, the proportions of warm and cold air 
delivered to the room can be varied, thus regulating the temperature 
without diminishing to any great extent the quantity of air delivered 



The objection to this form of damper is that there is a tendency for 
the air to enter the room before it is thoroughly mixed; that is, a 
stream of warm air will rise through one half of the register while 





















































HEATING AND VENTILATION 


79 


cold air enters through the other. This is especially true if the con¬ 
nection between the damper and register is short. Fig. 61 shows 
a similar heater and mixing damper, with brick casing. Cold air is 
admitted to the large chamber below the heater, and rises through 
the sections to the register as before. The action of the mixing 
damper is the same as already described. Several flues or registers 
may be connected with a stack of this form, each connection having, 
in addition to its mixing damper, an adjusting damper for regulating 
the flow of air to the different rooms. 

Another way of proportioning the air-flow in cases of this kind 
is to divide the hot-air chamber above the heater into sections, by 
means of galvanized-iron partitions, giving to each room its proper 
share of heating surface. If the cold-air supply is made sufficiently 
large, this arrangement is preferable to using adjusting dampers as 



described above. The partitions should be carried down the full 
depth of the heater between the sections, to secure the best results. 

The arrangement shown in Fig. 62 is somewhat different, and 
overcomes the objection noted in connection with Fig. 60, by sub¬ 
stituting another. The mixing damper in this case is placed at the 
other end of the heater. When it is in its highest position, all of the 
air must pass through the heater before reaching the register; but 
when partially lowered, a part of the air passes over the heater, 
and the result is a mixture of cold and warm air, in proportions 
depending upon the position of the damper. As the layer of warm 
air in this case is below the cold air, it tends to rise through it, and a 
more thorough mixture is obtained than is possible with the damper 
shown in Fig. 60. One quite serious objection, however, to this form 
of damper, is illustrated in Fig. 63. When the damper is nearly 


89 




















80 


HEATING AND VENTILATION 


P. it 


closed so that the greater part of the air enters above the heater, it 
has a tendency to fall between the sections, as shown by the arrows, 
and, becoming heated, rises again, so that it is impossible to deliver 

air to a room below a certain tem¬ 
perature. This peculiar action in¬ 
creases as the quantity of air admit¬ 
ted below the heater is diminished. 
When the inlet register is placed in 
the wall ai some distance above 


Fig. 63. Showing Difficulty of Regulat¬ 
ing Temperature with Arrangement 
in Fig. 62. 


the floor, as in schoolhouse work, a thorough mixture of air can be 
obtained by plac¬ 


ing the heater so 
that the current 
of warm air will 
pass up the front 
of the flue and be 
discharged into 
the room through 
the lower part of 
the register. This 
is shown quite 
clearly in Fig. 64, 
where the cur¬ 
rent of warm air 
is represented by 
crooked arrows, 
and the cold air 
by straight ar¬ 
rows. The two 
currents pass up 
the flue separate¬ 
ly; but as soon 
as they are dis¬ 
charged through 
the register the 
warm air tends 





Fig. 64. Arrangement of Heater and Damper Causing Warm Air 
to Enter Room through Lower Part of Register, thus 
Securing Thorough Mixing 


to rise, and the cold air to fall, with the result of a more or less 
complete mixture, as shown. 



































HEATING AND VENTILATION 


81 


It is often desirable to warm a room at times when ventilation 
is not necessary, as in the case of living rooms during the night, or 
for quick warming in the morning. A register and damper for air 
rotation should be provided in this case. Fig. 65 shows an arrange¬ 
ment for this purpose. When the damper is in the position shown, 
air will be taken from the room above and be warmed over and over; 
but, by raising the damper, the supply will be taken from outside. 
Special care should be taken to make all mixing dampers tight against 
air-leakage, else their advantages will be lost. They should work 
easily and close tightly against flanges covered with felt. They may 
be operated from the rooms above by means of chains passing over 



guide-pulleys; special attachments should be provided for holding 
in any desired position. 

Warm=Air Flues. The required size of the warm-air flue between 
the heater and the register, depends first upon the difference in tem¬ 
perature between the air in the flue and that of the room, and second, 
upon the height of the flue. In dwelling-houses, wher^ithe con¬ 
ditions are practically constant, it is customary to allow 2 square 
inches area for each square foot of radiation when the room'is on the 
first floor, and 1^ square inches for the second and third floors. In 
the case of hospitals, where a greater volume of air is required, these 
figures may be increased to 3 square inches for the first floor wards, 
and 2 square inches for those on the upper floors. 

In schoolhouse work, it is more usual to calculate the size of 
flue from an assumed velocity of air-flow through it. This will vary 
greatly according to the outside temperature and the prevailing wind 
conditions. The following figures may be taken as average velocities 


91 




















82 


HEATING AND VENTILATION 


obtained in practice, and may be used as a basis for calculating the 
reauired flue areas for the different stories of a school building: 

B 

1st floor, 280 feet per minute. 

2nd “ , 340 “ “ 

3rd " , 400 “ “ 

These velocities will be increased somewhat in cold and windy weather I 
and will be reduced when the atmosphere is mild and damp. 

Having assumed these velocities, and knowing the number of 
cubic feet of air to be delivered to the room per minute, we have only 
to divide this quanity by the assumed velocity, to obtain the required 
flue area in square feet. 

Example. A schoolroom on the second floor is to have an air-supply of 
2,000 cubic feet per minute. What will be the required flue area? 

Ans. 2000 -4- 340 = 5.8 + sq. feet. 
The velocities would be higher in the coldest weather, and dampers 
should be placed in the flues for throttling the air-supply when nec¬ 
essary. 

Cold=Air Ducts. The cold-air ducts supplying heaters should 
be planned in a manner similar to that described for furnace heating. 
The air-inlet should be on the north or west side of the building; but 
this of course is not always possible. The method of having a large 
trunk line or duct with inlets on two or more sides of the building, 
should be carried out when possible. A cold-air room with large 
inlet windows, and ducts connecting with the heaters, makes a good 
arrangement for schoolhouse work. The inlet windows in this case 
should be provided with check-valves to prevent any outward flow of 
air. A detail of this arrangement is shown in Fig. 66. 

This consists of a boxing around the window, extending from 
the floor to the ceiling. The front is sloped as shown, and is closed 
from the ceiling to a point below the bottom of the window. The 
remainder is open, and covered with a wire netting of about J-inch 
mesh; to this are fastened flaps or checks of gossamer cloth about 
6 inches in width. These are hemmed on both edges and a stout 
wire is run through the upper hem which is fastened to'the netting 
by means of small copper or soft iron wire. The checks allow the air 
to flow inward but close when there is any tendency for the current 
to reverse. 

The area of the cold-air duct for any heater should be about 
three-fourths the total area of the warm-air ducts leading from it. 

92 




HEATING AND VENTILATION 


83 


If the duct is of any considerable length or contains sharp bends, it 
should be made the full size of all the warm-air ducts. Adjusting 
dampers should be placed in the supply duct to each separate stack. 
If a trunk with two inlets is used, each inlet should be of sufficient 
size to furnish the full amount of air required, and should be pro¬ 
vided with cloth checks for preventing an outward flow of air, as 
already described. The inlet windows should be provided with 
some form of damper or slide, outside of which should be placed a 
wire grating, backed by a netting of about f-inch mesh. 

Vent Flues. In dwelling-houses, vent flues are often omitted, 
and the frequent opening of doors and leakage are depended upon to 
carry away the im¬ 
pure air. A well- 
designed system of 
warming should 
provide some means 
for discharge ven¬ 
tilation, especially 
for bathrooms and 
toilet-rooms, and 
also for living rooms 
where lights are 
burned in the even¬ 
ing. Fireplaces are 
usually provided in 
the more important 
rooms of a well- 
built house, and 
these are made to 
serve as vent flues. In rooms having no fireplaces, special flues 
of tin or galvanized iron may be carried up in the partitions in 
the same manner as the warm-air flues. These should be gathered 
together in the attic, and connected with a brick flue running up 
beside the boiler or range chimney. 

Very fair results may be obtained by simply letting the flues open 
•nto an unfinished attic, and depending upon leakage through the 
?oof to carry away the foul air. 



93 






















84 


HEATING AND VENTILATION 


The sizes of flues may be made the reverse of the warm-air flues 
—that is, 1J square inches area per square foot of indirect radiation 
for rooms on the first floor, and 2 square inches for those on the 
second. This is because the velocity of flow will depend upon the 
height of flue, and will therefore be greater from the first floor. The 
flow of air through the vents will be slow at best, unless some means 
is provided for warming the air in the flue to a temperature above 
that of the room with which it connects. 

The method of carrying up the outboard discharge beside a warm 
chimney is usually sufficient in dwelling-houses; but when it is 

desired to move larger 


Air 

Valve l 


Steam 


Return 


Fig. 67. Loop of Steam Pipe to be Run Inside Flue. 
Connected for Drainage and Air-Venting. 


quantities of air, a loop 
of steam pipe should be 
^in inside the flue. This 
should be connected for 
drainage and air-venting 
as shown in Fig. 67. 
When vents are carried 
through the roof inde¬ 
pendently, some form of 
protecting hood should 
be provided for keeping 
out the snow and rain. 
A simple form is shown 
in Fig. 68. Flues carried 
outboard in this way 
should always be ex¬ 


tended well above the ridges of adjacent roofs to prevent down 
drafts in windy weather. 

For schoolhouse work we may assume average velocities through 
the vent flues, as follows: 


1st floor, 340 feet per minute. 
2nd “ , 280 “ “ 

3rd “ , 220 “ “ 


Where flue sizes are based on these velocities, it is well to guard 
against down drafts by placing an aspirating coil in the flue. A 
single row of pipes across the flue as shown in Fig. 69, is usually 
sufficient for this purpose when the flues are large and straight; 


94 


















HEATING AND VENTILATION 85 

otherwise, two rows should be provided. The slant height of the 
heater should be about twice the depth of the flue, so that the area 
between the pipes shall equal the 
free area of the flue. 

Large vent flues of this kind 
should always be provided with 
dampers for closing at night, and 
for regulation during strong winds. 

Sometimes it is desired to move 
a given quantity of air through a 
flue which is already in place. 

Table XXIV shows what velocities 
may be obtained through flues of 
different heights, for varying dif¬ 
ferences in temperature between the 
outside air and that in the flue. 

Example .—It is desired to discharge 1,300 cubic feet of air per minute 
through a flue having an area of 4 square feet and a height of 30 feet. If the 
efficiency of an aspirating coil is 400 B. T. U., how many square feet of surface 
will be required to move this amount of air when the temperature of the room 
is 70° and the outside temperature is 60° ? 

3/ZfC V/EW 


Fig. 69. Aspirating Coil Placed in Flue to Prevent Down Drafts. 

1,300 4 = 325 feet per minute = Velocity through the flue. 

Looking in Table XXIV, and following along the line opposite a 
30-foot flue, we find that to obtain this velocity there must be a differ¬ 
ence of 30 degrees between the air in the flue and the external air. 





95 





































86 HEATING AND VENTILATION 

If the outside temperature is 60 degrees, then the air in the flue must 
be raised to 60 + 30 = 90 degrees. The air of the room being at 
70 degrees, a rise of 20 degrees is necessary. So the problem resolves 
itself into the following: What amount of heating surface having an 

TABLE XXIV 


Air=Flow through Flues of Various Heights under Varying 
Conditions of Temperature 

(Volumes given in cubic feet per square foot of sectional area of flue) 


Height of 
Flue 
in Feet 


5 

10 

15 

20 

25 

30 

35 

40 

45 

50 

60 


Excess of Temperature of Air in Flue Above that of External Air 


55 

77 

94 

108 

121 

133 

143 

153 

162 

171 

188 


10 ° 


76 

108 

133 

153 

171 

188 

203 

217 

230 

242 

264 


15° 


94 

133 

162 

188 

210 

230 

248 

265 

282 

297 

325 


109 

153 

188 

217 

242 

265 

286 

306 

325 

342 

373 


30° 


134 

188 

230 

265 

297 

325 

351 

375 

398 

419 

461 


50° 


167 

242 

297 

342 

383 

419 

453 

484 

514 

541 

594 


efficiency of 400 B. T. U. is necessary to raise 1,300 cubic feet of air 
per minute through 20 degrees? 

1,300 cubic feet per minute = 1,300 X 60 = 78,000 per hour; 
and making use of our formula for “heat for ventilation,” we have 
78,000 X 20 


55 


' = 28,363 B.T. U.; 


and this divided by 400 = 71 square feet of heating surface required. 
EXAMPLES FOR PRACTICE 


1. A schoolroom on the third floor has 50 pupils, who are 
to be furnished with 30 cubic feet of air per minute each. What will 
be the required areas in square feet of the supply and vent flues? 

Ans. Supply, 3.7 +. Vent, 6.8 +. 

2. What size of heater will be required in a vent flue 40 feet 
high and with an area of 5 square feet, to enable it to discharge 1,530 
cubic feet per minute, when the outside temperature is 60°? (Assume 
an efficiency of 400 B. T. U. for the heater.) Ans. 41.7 square feet. 


96 























HEATING AND VENTILATION 


87 


Registers. Registers are made of cast iron and bronze, in a 
great variety of sizes and patterns. The almost universal finish for 
cast-iron registers is black “Japan;” but they are also finished in 
colors and electroplated with 
copper and nickel. Fig. 70 
shows a section through a 
floor register, in which A rep¬ 
resents the valves, which may 
be turned in a veitical or hori¬ 
zontal position, thus opening 
or closing the register; B is the 
iron border; C, the register box 
of tin or galvanized iron; and D, the warm-air pipe. Floor registers 
are usually set in cast-iron borders, one of which is shown in Fig. 71; 
while wall registers may be screwed directly to wooden borders or 
frames to correspond with the finish of the room. Wall registers 
should be provided with pull-cords for opening and closing from the 
floor? these are shown in Fig. 72. The plain lattice pattern shown in 
Fig. 73 is the best for schoolhouse work, as it has a comparatively 

free opening for 
air-flow and is 
pleasing and sim¬ 
ple in design. 
More elaborate 
patterns are used 
for fine dwelling- 
house work. 
Registers with 
shut-off valves 
are used for air- 
inlets, while the 
plain register 
faces without the 
valves are placed 
in the vent open¬ 
ings. The vent flues are usually gathered together in the attic, and 
a single damper may be used to shut off the whole number at once. 
Flat or round wire gratings of open pattern are often used in place of 



Fig. 71. Cast-Iron Border for a Floor Register. 



Fig. 70.. Section through a Floor Register. 


97 



























88 HEATING AND VENTILATION 

register faces. The grill or solid part of a register face usually takes 
up about J of the area; hence in computing the size, we must allow 
for this by multiplying the required “net area” by 1.5, to obtain the 
“total” or “over-all” area. 

Example. Suppose we have a flue 10 inches in width and wish to use a 
register having a free area of 200 square inches. What will be the required 
height of the register? 

200 X 1 • 5 = 300 square inches, which is the total area required; 
then 300 -5- 10 = 30, which is the required height, and we should use 
a 10 by 30-inch register. When a register is spoken of as a 10 by 



Fig. 72. Wall Register with Pull Fig. 73. Plain Lattice Pattern Register. Best 
Cords for Opening and for Schoolhouse W ork. 

Closing. 


30-inch or a 10 by 20-inch, etc., the dimensions of the latticed opening 
are meant, and not the outside dimensions of the whole register. The 
free opening should have the same area as the flue with which it con¬ 
nects. In designing new work, one should provide himself with a 
trade catalogue, and use only standard sizes, as special patterns and 
sizes are costly. Fig. 74 shows the method of placing gossamer 
check-valves back of the vent register faces to prevent down drafts, 
the same as described for fresh-air inlets. 


98 


















































HEATING AND VENTILATION 


89 


Inlet registers in dwelling-house and similar work are placed 
either in the floor or in the baseboard; sometimes they are located 
under the windows, just above the baseboard. The object in view 
is to place them where the currents of air entering the room will not 
be objectionable to persons sitting near windows. A long, narrow 
floor-register placed close to the wall in front of a window, sends 
up a shallow current of warm air, which is not especially noticeable 



Fig. 74. Method of Placing Gossamer Check-Valves back of Vent Register Face 
to Prevent Down Drafts. 


to one sitting near it. Inlet registers are preferably placed near 
outside walls, especially in large rooms. Vent registers should be 
placed in inside walls, near the floor. 

Pipe Connections. The two-pipe system with dry or sealed 
returns is used in indirect heating. The conditions to be met are 
practically the same as in direct heating, the only difference being 
that the radiators are at the basement ceiling instead of on the floors 
above. The exact method of making the pipe connections will 
depend somewhat upon existing conditions; but the general method 
shown in Fig. 75 may be used as a guide, with modifications to suit 


99 



















90 


HEATING AND VENTILATION 


any special case. The ends of all supply mains should be dripped, 
and the horizontal returns should be sealed if possible. 

Pipe Sizes. The tables already given for the proportioning of 
pipe sizes can be used for indirect systems. The following table has 
been computed for an efficiency of 040 B. T. U. per square foot of 
surface per hour, which corresponds to a condensation of § of a pound 
of steam. This is twice that allowed for direct radiation in Table 


A/R 
valve :p 


f 

IT 


HEATER 


CASING 


o 


SUPPLY 




HR/P 


WATER L/NE 


a 


MAIN RETURN 


Fie. 75. General Method of Making Pipe and Radiator Connections, in Basement, 
in Indirect Keating. 

XVII; so that we can consider 1 square foot of indirect surface as 
equal to 2 of direct in computing pipe sizes. 

As the indirect heaters are placed in the basement, care must be 
taken that the bottom of the radiator does not come too near the 
water-line of the boiler, or the condensation will not flow back prop¬ 
erly; this distance, under ordinary conditions, should not be less than 
2 feet. If much less than this, the pipes should be made extra large, 
§o that there may be little or no drop in pressure between the boiler 


100 















































HEATING AND VENTILATION 


91 


TABLE XXV 


Indirect Radiating Surface Supplied by Pipes of Various Sizes 


Size of Pipe 

Square Feet of Indirect Radiation which will be Supplied with 


1 Pound Drop in 200 Feet 

\ Pound Drop in 100 Feet 

h Pound Drop in 100 Feet 

1 in. 

28 

40 

57 

H“ 

51 

72 

105 

1* “ 

67 

95 

170 

2 “ 

185 

262 

375 

2 \ “ 

335 

475 

675 

3 “ 

540 

775 

1,105 

3£ “ 

812 

1, 160 

1,645 

2, 310 

4 “ 

1, 140 

1, 625 

5 “ 

2, 030 

2 , 900 

4, 110 

6 

3, 260 

4, 660 

6, 600 

7 “ 

4, 830 

6, 900 

9, 810 

8 “ 

6, 800 

' 9,720 

13, 860 


and the heater. A drop in pressure of 1 pound would raise the 
water-line at the heater 2.4 feet. 



Fig 76. General Form of Direct-Indirect Fig. 77. Section through Radiator Shown 
Radiator. * in Fig. 76. 


Direct=Indirect Radiators. A direct-indirect radiator is similar 
in form to a direct radiator, and is placed in a room in the same 




















































92 


HEATING AND VENTILATION 


manner. 


_ Fig. 76 shows the general form of this type of radiator; 

and Fig. 77 shows a section through the same. The shape of the 
sections is such, that when in place, small flues are formed between 
them. Air is admitted through an opening in the outside wall, and, 
in passing upward through these flues, becomes heated before enter¬ 
ing the room. A switch-damper is placed in the duct at the base of 
the radiator, so that the air may be taken from the room itself instead 
' f from out of doors, if so desired. This is shown more particularly 
in Fig. 76. 

Fig. 78 shows the wall box provided with louvre slats and netting, 
through which the air is drawn. A damper door is placed at either 

end of the radiator base; 
and, if desired, when the 
cold-air supply is shut off 
by means of the register 
in the air-duct, the radia¬ 
tor can be converted into 
the ordinary type by 
opening both damper 
doors, thus taking the air 
from the room instead 
of from the outside. It is customary to increase the size of a direct- 
indirect radiator 30 per cent above that called for in the case of 
direct heating. 





Fig. 78. Wall Box with Louvre Slats and Netting, 
Direct-Indirect System. 


CARE AND MANAGEMENT OF STEAM= 
HEATING BOILERS 


Special directions are usually supplied by the maker for each 
kind of boiler, or for those which are to be managed in any peculiar 
way. The following general directions apply to all makes, and may 
be used regardless of the type of boiler employed: 

Before starting the fire, see that the boiler contains sufficient 
water. The water-line should be at about the center of the gauge- 
glass. 

The smoke-pipe and chimney flue should be clean, and the draft 
good. 

Build the fire in the usual way, using a quality of coal which is 
best adapted to the heater. In operating the fire, keep the firepot 


102 


22H5 








HEATING AND VENTILATION 


93 


full of coal, and shake down and remove all ashes and cinders as often 
as the state of the fire requires it. 

Hot ashes or cinders must not be allowed to remain in the ashpit 
under the grate-bars, but must be removed at regular intervals to 
prevent burning out the grate. 

To control the fire, see that the damper regulator is properly 
attached to the draft doors and the damper; then regulate the draft 
by weighting the automatic lever as may be required to obtain the 
necessary steam pressure for warming. Should the water in the 
boiler escape by means of a broken gauge-glass, or from any other 
cause, the fire should be dumped, and the boiler allowed to cool before 
adding cold water. 

An empty boiler should never be filled when hot. If the water 
gets low at any time, but still shows in the gauge-glass, more water 
should be added by the means provided for this purpose. 

The safety-valve should be lifted occasionally to see that it is 
in working order. 

If the boiler is used in connection with a gravity system, it should 
be cleaned each year by filling with pure water and emptying through 
the blow-off. If it should become foul or dirty, it can be thoroughly 
cleansed by adding a few pounds of caustic soda, an? allowing it to 
stand for a day, and then emptying and thoroughly rinsing. 

During the summer months, it is i ecommended that the water 
be drawn off from the system, and that air-valves and safety-valves 
be opened to permit the heater to dry out and to remain so. Good 
results, however, are obtained by filling the heater full of water, 
driving off the air by boiling slowly, and allowing it to remain in this 
condition until needed in the fall. The water should then be drawn 
off and fresh water added. 

The heating surface of the boiler should be kept clean and free from 
ashes and soot by means of a brush made especially for this purpose. 

Should any of the rooms fail to heat, examine the steam valves 
in the radiators. If a two-pipe system, both valves at each radiator 
must be opened or closed at the same time, as required. See that 
the air-valves are in working condition. 

If the building is to be unoccupied in cold weather, draw all the 
water out of the system by opening the blow-off pipe at the boiler and 
all steam valves and air-valves at the radiators. 


103 



94 


HEATING AND VENTILATION 


HOT=WATER HEATERS 




Types. Hot-water heaters differ from steam boilers principally 
in the omission of the reservoir or space for steam above the heating 
surface. The steam boiler might answer as a heater for hot water; 

but the large capacity left for 
the steam would tend to make 
its operation slow and rather 
unsatisfactory, although the 
same type of boiler is some¬ 
times used for both steam and 
hot water. The passages in 
a hot-water heater need not 
extend so directly from bot¬ 
tom to top as in a steam boil¬ 
er, since the problem of pro¬ 
viding for the free liberation 
of the steam bubbles does not 
have to be considered. In 
general, the heat from the 
furnace should strike the sur¬ 
faces in such a manner as to 
increase the natural circula¬ 
tion ; this may be accomplished 
to a certain extent by arrang¬ 
ing the heating surface so that 
a large proportion of the 
direct heat will be absorbed 
near the top of the heater. 
Practically the boilers for low- 
pressure steam and for hot 
water differ from each other 
very little as to the character 
of the heating surface, so that 
the methods already given for 
computing the size of grate 

Jig. 79. Top—Richardson Sectional Hot-Water ^ ° 

Heater. Bottom—Same Heater Equipped Surface, llOrse-pOWer, etc., 
as Steam Boiler. 7 1 ’ 7 

Courtesy of Richardson and Boynton, New York City. Ullder the head of ^SteaiQ 


104 






HEATING AND VENTILATION 95 

Boilers, can be used with satisfactory results in the case of hot- 
water heaters. 

It is sometimes stated that, owing to the greater difference in 
temperature between the furnace gases and the water in a hot-water 
heater, as compared with steam, the heating surface will be more 
efficient and a smaller heater can be used. While this is true to a 
certain extent, different authorities agree that this advantage is so 
small that no account should be taken of it, and the general propor¬ 
tions of the heater should be calculated in the same manner as for 
steam. Fig. 79 shows a form of heater made up of slabs or sections 
similar to the sectional steam boiler shown in Part I. The size can 
be increased in a similar manner, by adding more sections. In this 
case, however, the boiler is increased in width instead of in length. 
This has an advantage 
in the larger sizes, as 
a second fire door can 
be added, and all parts 
of the grate can be 
reached as well in the 
large sizes as in the 
small. 

Fig. 80 shows a 
boiler consisting of fire 
pot, feed section, inter¬ 
mediate reservoir, and 
a cored top. This 
boiler is circular in 
form and well adapted 
to dwelling-houses and similar work. The cut at the left shows the 
boiler equipped for steam by the attachment of gages and water glass. 
The cut at the right shows the proper equipment for the hot-water 
system, the heater being shown in part sections to give an idea of the 
construction. 

Fig. 81 shows another type of sectional cast-iron heater. A 
deep fire chamber with corrugated sides makes this furnace a quick 
heater and keeps the fire a long time without attention. The space 
between the outer and inner corrugated shells surrounding the fur¬ 
nace, as shown by the part section in Fig. 81, is filled with water, 



Fig. 80. “Standard” Boiler, with Sections Superposed. 
Courtesy of Giblin and Company, Utica, New York. 


105 










96 


HEATING AND VENTILATION 



as is also the case with the cross-pipes directly over the fire and the 
drum at the top. 

The ordinary horizontal and vertical tubular boilers, with various 
modifications, are used to a considerable extent for hot-water heating, 
and are well adapted to this class of work, especially in the case of 
large buildings. 

Automatic regulators are often used for the purpose of main¬ 
taining a constant temperature of the water. They are constructed 

in different ways—some de¬ 


pend upon the expansion of a 
metal pipe or rod at different 
temperatures, and others upon 
the vaporization and conse¬ 
quent pressure of certain vol¬ 
atile liquids. These means are 
usually employed to open 
small valves which admit 
water pressure under rubber 
diaphragms; and these in turn 
are connected by means of 
chains with the draft doors 
of the furnace, and so regulate 
the draft as required to main¬ 
tain an even temperature of 
the water in the heater. Fig. 
82 shows one of the first kind. 
A is a metal rod placed in the 
flow pipe from the heater, and 
is so connected with the valve 
B that when the water reaches 
a certain temperature the expansion of the rod opens the valve and 
admits water from the street pressure through the pipes C and D into 
the chamber E. The bottom of E consists of a rubber diaphragm, 
which is forced down by the water pressure and carries with it the 
lever which operates the dampers as shown, and checks the fire. 
When the temperature of the water drops, the rod contracts and 
valve B closes, shutting off the pressure from the chamber E. A 
spring is provided to throw the lever back to its original position, 


Fig. 81. Cast-Iron Heater Made in Sections. 
Water Fills Space Between Outer and 
Inner Shells and Drum at Top. 

Courtesy of Richardson and Boynton Company , 
New York City. 


106 




HEATING AND VENTILATION 


97 


and the water above the diaphragm is forced out through the pet- 
cock G, which is kept slightly open all the time. 

DIRECT HOT=WATER HEATING 

A hot-water system is similar in construction and operation to 
one designed for steam, except that hot water flows through the 
pipes and radiators instead. 

The circulation through the pipes is produced solely by the dif¬ 
ference in weight of the 
water in the supply and 
return, due to the differ- 
ence in temperature. 

When water is heated it 
expands, and thus a 
given volume becomes 
lighter and tends to rise, 
and the cooler water flows 
in to take its place; if the 
application of heat is kept 
up, the circulation thus 
produced is continuous. 

The velocity of flow de¬ 
pends upon the difference 
in temperature between 
the supply and return, 
and the height of the 
radiator above the boiler. 

The horizontal distance 
of the radiator from the 
boiler is also an important factor affecting the velocity of flow. 

This action is best shown by means of a diagram, as in Fig. 83. 
If a glass tube of the form shown in the figure is filled with water and 
held in a vertical position, no movement of the water will be noticed, 
because the two columns A and B are of the same weight, and there¬ 
fore in equilibrium. Now, if a lamp flame be held near the tube A, 
the small bubbles of steam which are formed will show the water 
to be in motion, with a current flowing in the direction indicated by 
the arrows. The reason for this is, that, as the water in A is heated. 



107 


































98 


HEATING AND VENTILATION 


reed 




it expands and becomes lighter for a given volume, and is forced 
upward by the heavier water in B falling to the bottom of the tube. 
The heated water flows from A through the connecting tube at the 
top, into B, where it takes the place of the 
cooler water which is settling to the bottom. If, 
now, the lamp be replaced by a furnace, and the 
columns A and B be conhected at the top by 
inserting a radiator, the illustration will assume 
the practical form as utilized in hot-water heating 
(see Fig. 84). 

The heat given off by the radiator always 
insures a difference in temperature between the 
columns of water in the supply and return pipes 
so that as long as heat is supplied by the furnace 
the flow of water will continue. The greater the 


i" 


3EE# 


Fig. 83. Illustrating 
How the Heating 
of Water Causes 
Circulation. 


£XPANS/ON TANK 


PAD/ATOR 


difference in temperature of the water in the two pipes, the greater 
the difference in weight, and con¬ 
sequently the faster the flow. The 
greater the height of the radiator 
above the heater, the more rapid 
will be the circulation, because the 
total difference in weight between 
the water in the supply and return 
risers will vary directly with their 
height. From the above it is evident 
that the rapidity of flow depends 
chiefly upon the temperature differ¬ 
ence between the supply and return, 
and upon the height of the radiator 
above the heater. Another factor 
which must be considered in long 
runs of horizontal pipe is the fric¬ 
tional resistance. 

Systems of Circulation. There 
are two distinct systems of cir¬ 
culation employed—one depending 
on the difference in temperature 



Fig. 84. Illustrating Simple Circula¬ 
tion in a Heating System. 


of the water in the supply and return pipes, called gravity circulation ; 
































HEATING AND VENTILATION 


99 


and another where a pump is used to force the water through the 
mains, called forced circulation. The former is used for dwellings 
and other buildings of ordinary size, and the latter for large buildings, 
and especially where there are long horizontal runs of pipe. 

For gravity circulation some form of sectional cast-iron boiler 
is commonly used, although wrought-iron tubular boilers may be 
employed if desired. In the case of forced circulation, a heater de- 
i signed to warm the water by means of live or exhaust steam is often 
| used. A centrifugal or rotary pump is best adapted to this pur- 
I pose, and may be driven by an electric motor or a steam engine, 
as most convenient. 

Types of Radiating Surface. Cast-iron radiators and circulation 
j coils are used for hot water as 
well as for steam. Hot-water 
radiators differ from steam 
radiators principally in having 
a horizontal passage at the top 
as well as at the bottom. 

This construction is necessary 
in order to draw off the air 
which gathers at the top of 
each loop or section. Other¬ 
wise they are the same as 
steam radiators, and are well 

for tV.#* ^irniilafinn n f Fig. S5. Showing Construction of Radiator for 
adapted tor tne circulation Ot Hot Water or Steam. Note Horizontal Pas- 

steam, and in some respects sage along Top. 

i are superior to the ordinary pattern of steam radiator. 

The form shown in Fig. 85 is made with an opening at the top 
lor the entrance of water, and at the bottom for its discharge, thus 
insuring a supply of hot water at the top and of colder water at the 
bottom. 

Some hot-water radiators are piade with a cross-partition so 
arranged that all water entering passes at once to the top, from which 
it may take any passage toward the outlet. Fig. 86 is the more 
common form of radiator, and is made with continuous passages at 
top and bottom, the hot water being supplied at one side and drawn 
off at the other. The action of gravity is depended upon for making 
the hot and lighter water pass to ’the top, and the colder water sink 



109 



































100 


HEATING AND VENTILATION 

to the bottom and flow off through the return. Hot-water radiators 
are usually tapped and plugged so that the pipe connections can be 
made either at the top or at the bottom. This is shown in Fig. 87. < 
Wall radiators are adapted to hot-water as well as steam heating. 
Efficiency of Radiators. The efficiency of a hot-water radiator 
depends entirely upon the temperature at which the water is circu¬ 
lated. The best practical results are obtained with the water leaving 
the boiler at a maximum temperature of about 180 degrees in zero 
weather and returning at about 1G0 degrees; this gives an average 



Fig. 86. Common Form of Hot-Water Radiator. Circulation Fig. 87. End Elevation of 
Produced Wholly through Action of Gravity, Hot Radiator Showing Taps 

Water Rising to Top. at Top and Bottom for 

Pipe Connections. 


temperature of 170 degrees in the radiators. Variations may be made, 
however, to suit the existing conditions of outside temperature. We 
have seen that an average cast-iron radiator gives off about 1.7 B.T.U. 
per hour per square foot of surface per degree difference in tempera¬ 
ture between the radiator and the surrounding air, when working 
under ordinary conditions; and this holds true whether it is filled 
with steam or water. 

If we assume an average temperature of 170 degrees for the 
water, then the difference in temperature between the radiator and 
the air will be 170 — 70 = 100 degrees; and this multiplied by 1.7 = 


110 



























































HEATING AND VENTILATION 


101 


170, which may be taken as the efficiency of a hot-water radiator 
under the above average conditions. 

T his calls for a water radiator about 1.5 times as large as a steam 
radiator to heat a given room under the same conditions. This is 
common practice although some engineers multiply by the factor 1.6, 
which allows for a lower temperature of the water. Water leaving 
the boiler at 170 degrees should return at about 150; the drop in 
temperature should not ordinarily exceed 20 degrees. 

Systems of Piping. A system of hot-water heating should pro¬ 
duce a perfect circulation of water from the heater to the radiating 



Fig. 88. System of Piping Usually Employed for Hot-Water Heating. 


surface, and thence back to the heater through the returns. The 
system of piping usually employed for hot-water heating is shown in 
Fig. 88. In this arrangement the main and branches have an inclina¬ 
tion upward from the heater; the returns are parallel to the mains, 
and have an inclination downward toward the heater, connecting 
with it at the lowest point. The flow pipes or risers are taken from 
the tops of the mains, and may supply one or more radiators as 
required. The return risers or drops are connected with the return 
mains in a similar manner. In this system great care must be taken 
to produce a nearly equal resistance to flow in all of the branches, so 
that each radiator may receive its full supplv of water. It will always 


111 





































































102 


HEATING AND VENTILATION 


be found that the principal current of heated water will take the path 
of least resistance, and that a small obstruction or irregularity in the 
piping is sufficient to interfere greatly with the amount of heat received 
in the different parts of the same system. 

Some engineers prefer to carry a single supply main around the 
building, of sufficient size to supply all the radiators, bringing back 
a single return of the same size. Practice has shown that in general 
it is not well to use pipes over 8 or. 10 inches in diameter; if larger 
pipes are required, it is better to run two or more branches. 

The boiler, if possible, should be centrally located, and branches 

carried to differ- 

Exp.Ta.rVU 


□ 


Boiler 


Fig. 89. System of Hot-Water Piping Especially Adapted to 
Apartment Buildings where Each Flat Has a Separate Heater. 


ent parts of the 
building. This 
insures a more 
even circulation 
than if all the 
radiators are 
supplied from a 
single long main, 
in which case 
the circulation 
is liable to be 
sluggish at the 
farther end. 

The arrange¬ 
ment shown in 
Fig. 89 is similar 


to the circuit system for steam, except that the radiators have two 
connections instead of one. This method is especially adapted to 
apartment houses, where each flat has its separate heater, as it 
eliminates a separate return main, and thus reduces, by practically 
one-half, the amount of piping in the basement. The supply risers 
are taken from the top of the main; while the returns should con¬ 
nect into the side a short distance beyond, and in a direction away 
from the boiler. When this system is used, it is necessary to enlarge 
the radiators slightly as the distance from the boiler increases. 

In flats of eight or ten rooms, the size of the last radiator may be 
increased from 10 to 15 per cent, and the intermediate ones propor- 


112 
































HEATING AND VENTILATION 


103 


tionaily, at the same time keeping the main of a large and uniform 
size for the entire circuit. 

Overhead Distribution. This system of piping is shown in Fig. 
90. A single riser is carried directly to the expansion tank, from 
which branches are taken to supply the various drops to which the 
radiators are connected. An important advantage in connection 
with this system is that the air rises at once to the^expansion tank, 
and escapes through the vent, so that air-valves are not required on 
the radiators. 



Fig. 90. “Overhead” Distribution System of Hot-Water Piping. 


At the same time, it has the disadvantage that the water in the 
tank is under less pressure than in the heater; hence it will boil at 
a lower temperature. No trouble will be experienced from this, how¬ 
ever, unless the temperature of the water is raised above 212 degrees. 

Expansion Tank. Every system for hot-water heating should be 
connected with an expansion tank placed at a point somewhat above 
the highest radiator. The tank must in every case be connected to a 
line of piping which cannot by any possible means be shut off from 
the boiler. When water is heated, it expands a certain amour*,. 


113 
























104 


HEATING AND VENTILATION 



depending upon the temperature to which it is raised; and a tank or 
reservoir should always be provided to care for this increase in volume. 

Expansion tanks are usually made of heavy galvanized iron of 
one of the forms shown in Figs. 91 and 92, the latter form Deing used 

where the headroom is limited. The 
connection from the heating system 
enters the bottom of the tank, and 
an open vent pipe is taken from the 
top. An overflow connected with 
a sink or drain-pipe should be 
provided. Connections should be 
made with the water supply both 
at the boiler and at the expansion 
tank, the former to be used when 
first filling the system, as by this 
means all air is driven from the bot¬ 
tom upward and is discharged 
through the vent at the expansion 
tank. Water that is added after¬ 
ward may be supplied directly to the 
expansion tank, where the water-line can be noted in the gauge-glass, 
A ball-cock is sometimes arranged to keep the water-line in the tank 
at a constant level. 

An altitude 
gauge is often 
placed in the base¬ 
ment with the col¬ 
ored hand or point- ^ ooy' 
er set to indicate 
the normal water¬ 
line in the expan¬ 
sion tank. When 
the movable hand 
falls below the 
fixed one, more 
water may be added, as required, through the supply pipe at the boiler. 
When the tank is placed in an attic or roof space where there is danger 
of freezing, the expansion pipe may be connected into the side of the 


CONNECTION 

rnosA 

SYSTEM 


Fig. 91. A Common Form of Galvanized- 
Iron Expansion Tank. 


•ft 


VENT P/PC 


WATER L/NE 


OVEAfElOW 


CONNECT/ ON 
FROM 
SYSTEM 

Fig. 92. Form of Expansion Tank Used where Headroom 
is Limited. 


114 

































HEATING AND VENTILATION 


105 


tank, 6 or 8 inches from the bottom, and a circulation pipe taken 
from the lower part and connected with the return from an upper- 
floor radiator. This produces a slow circulation through the tank, 
and keeps the water warm. 

The size of the expansion tank depends upon the volume of 
water contained in the system, and on the temperature to which it is 
heated. The following rule for computing the capacity of the tank 
may be used with satisfactory results: 

Square feet of radiation, divided by 40, equals required capacity of 
tank in gallons. 

Air=Venting. One very important point to be kept in mind in 
the design of a hot-water system, is the removal of air from the pipes 
and radiators. When the water in the boiler is heated, the air it 
contains forms into small bubbles which rise to the highest points of the 
system. 

In the arrangement shown in Fig. 88, the main and branches 
grade upward from the boiler, so that the air finds its way into the 
radiators, from which it may be drawn off by means of the air-valves. 

A better plan is that shown in Fig. 89. In this case the expan¬ 
sion pipe is taken directly off the top of the main over the boiler, so 
that the larger part of the air rises directly to the expansion tank and 
escapes through the vent pipe. The same action takes place in the 
overhead system shown in Fig. 90, where the top of the main riser 
is connected with the tank. Every high point in the system and 
every radiator, except in the downward system with top supply con¬ 
nection, should be provided with an air-valve. 

Pipe Connections. There are various methods of connecting 
the radiators with the mains and risers. Fig. 93 shows a radiator 
connected with the horizontal flow and return mains, which are 
located below the floor. The manner of connecting with a vertical 
riser and return drop is shown in Fig. 94. As the water tends to 
flow to the highest point, the radiators on the lower floors should be 
favored by making the connection at the top of the riser and taking 
the pipe for the upper floors from the side as shown. Fig. 95 illus¬ 
trates the manner of connecting with a radiator on an upper floor where 
the supply is connected at the top of the radiator. 

The connections shown in Figs. 96 and 97 are used with the 
overhead system shown in Fig. 90. 


115 


106 


HEATING AND VENTILATION 


Where the connection is of the form shown at the left in Fig. 90, 
the cooler water from the radiators is discharged into the supply pipe 
again, so that the water furnished to the radiators on the lower floors 
is at a lower temperature, and the amount of heating surface must be 
correspondingly increased to make up for this lass, as already de¬ 
scribed for the circuit system. 


Pig 93 Radiator Connected with Hori* Fig. 94. Radiator Connected to Vertical 
zontal Plow and Return Mains Riser and Return Drop. 

Located below Floor. 




For example, if in the case of Fig. 90 we assume the water to 
leave at 180 degrees and return at 160, we shall have a drop in tem¬ 
perature of 10 degrees on each floor; that is, the water will enter the 
radiator on the second floor at ISO degrees and leave it at 170, and 
will enter the radiator on the first floor at 170 and leave it at 160. 



Fig. 95. Upper-Floor Radiator with Sup- Fig 96. Radiator Connections. Overhead 
ply Connected at 1 op. Distribution System. 

The average temperatures will be 175 and 165, respectively. The 
efficiency in the first case will be 175 — 70 = 105; and 105 X 1.5 = 
157. In the second case, 165 — 70 = 95; and 95 X 1.5 = 142; 
so that the radiator on the first floor will have to be larger than that 
on the second floor in the ratio of 157 to 142, in order to do the same 
work. 


116 














































































































































HEATING AND VENTILATION 


107 




AAA 


M 


This is approximately an increase of 10 per cent for each story 
downward to offset the cooling effect; but in practice the supply 
drops are made of such size that only a part of the water is by-passed 
through the radiators. For this reason an increase of 5 per cent 
for each story downward is probably sufficient in ordinary cases. 

Where the radiators discharge 
into a separate return as in the case 
of Fig. 88, or those at the right in 
Fig. 90, we may assume the tempera¬ 
ture of the water to be the same on 
all floors, and give the radiators an 
equal efficiency 

In a dwelling-house of two stories, 
no difference would be made in the 
sizes of radiators on the two floors; 
but in the case cf a tall office build¬ 
ing, corrections would necessarily be made as above described. 

Where circulation coils are used, they should be of a form which 
will tend to produce a flow of water through them. Figs. 98, 99, and 
100 show different ways of making up and connecting these coils. 
In Figs. 98 and 100, supply pipes may be either drops or risers; and 



Fig. 97. Another Form of Radiator 
Connection, Overhead Distribu¬ 
tion System. 



in the former case the return in Fig. 100 may be carried back, if desired 
into the supply drop, as shown by the dotted lines. 

Combination Systems. Sometimes the boiler and piping are 
arranged for either steam or hot water, since the demand for a higher 
or lower temperature of the radiators might change. 


117 





























































108 


HEATING AND VENTILATION 


The object of this arrangement is to secure the advantages of a 
hot-water system for moderate temperatures, and of steam heating 
for extremely cold weather. 



Fig. 99. Another Method of Building Up a Circulation Coil. 


As less radiating surface is required for steam heating, there is 
an advantage due to the reduction in first cost. This is of consider¬ 
able importance, as a heating system must be designed of such dimen¬ 
sions as to be capable of warming a building in the coldest weather; 



and this involves the expenditure of a considerable amount for radiat¬ 
ing surfaces, which are needed only at rare intervals. A combination 
system of hot-water and steam heating requires, first , a heater or boiler 


118 













































HEATING AND VENTILATION 


109 


which will answer for either purpose; second , a system of piping 
which will permit the circulation of either steam or hot water; and 
third, the use of radiators which are adapted to both kinds of heating. 
These requirements will be met by using a steam boiler provided with 
all the fittings required for steam heating, but so arranged that the 
damper regulator may be closed by means of valves when the system 
is to be used for hot-water heating. The addition of an expansion 
tank is required, which must be so arranged that it can be shut off 
when the system is used for steam heating. The system of piping 
shown in Fig. 88 is best adapted for a combination system, although 
an overhead distribution as shown in Fig. 90 may be used by shutting 
off the vent and overflow pipes, and placing air-valves on the radiators. 

While -this system has many advantages in the way of cost over 
the complete hot-water system, the labor of changing from steam 
to hot water will in some cases be trouble¬ 
some; and should the connections to the 
expansion tank not be opened, serious re¬ 
sults would follow. 

Valves and Fittings. Gate-valves 
should always be used in connection with 
hot-water piping, although angle-valves may 
be used at the radiators. There are several 
patterns of radiator valves made especially 
for hot-water work; their chief advantage 
lies in a device for quick closing, usually a 
quarter-turn or half-turn being sufficient to 
open or close the valve. Two different designs are shown in Figs. 
101 and 102. 

It is customary to place a valve in only one connection, as that is 
sufficient to stop the flow of water through the radiator; a fitting 
known as a union elbow is often employed in place of the second valve. 
(See Fig. 103.) 

Air=Valves. The ordinary pet-cock air-valve is the most reliable 
for hot-water radiators, although there are several forms of auto¬ 
matic valves which are claimed to give satisfaction. One of these 
is shown in Fig. 104. This is similar in construction to a steam 
trap. As air collects in the chamber, and the water-line is lowered, 
the float drops, and in so doing opens a small valve at the top of the 



Fig. !0t. Radiator Valve for 
Hot-Water Work. 


119 















110 


HEATING AND VENTILATION , . 


chamber, which allows the air to escape. As the water flows in to take 
its place, the float is forced upward and the valve is closed. 

All radiators which are supplied by risers from below, should be 
provided with air-valves placed in the top 
of the last section at the return end. If 
they are supplied by drops from an over- 




Pig. 102. Another Type of Hot- 
Water Radiator Valve. 


Fig. 103. Union Elbow. 


head system, the air will be discharged at the expansion tank, and 
air-valves will not be necessary at the radiators. 

Fittings. All fittings, such as elbows, tees, etc., should be of 
the long-turn pattern. If the common form is used, they should be 

a size larger than the pipe, bushed 
down to the proper size. The long- 
turn fittings, however, are preferable, 
and give a much better appearance. 
Connections between the radiators 
and risers may be made with the 



ordinary short-pattern fittings, as 
those of the other form are not well 


Fig. 104. Automatic Air-Valve • for 
Hot-Water Radiator. Operated 
by a Float. 


adapted to the close connections nec¬ 
essary for this work. 

Pipe 1 Sizes. The size of pipe 
required to supply any given radiator 
depends upon four conditions; first, the 
size of the radiator; second, its elevation 
above the boiler; third, the length of 
pipe required to connect it with the 


boiler; and fourth , the difference in temperature between the supply 
and the return 


120 



































heating and ventilation 


111 




AxS ic would be a long and rather complicated process to work out 
the required size of each pipe for a heating system, Tables XXVI and 
XXVII have been prepared, covering the usual conditions to be met 
with in practice. 


TABLE XXVI 

Direct Radiating Surface Supplied by Mains of Different 
Sizes and Lengths of Run 



These quantities have been calculated on a basis of 10 feet difference 
in elevation between the center of the heater and the radiators, and a differ¬ 
ence in temperature of 17 degrees between the supply and the return. 


TABLE XXVII 

Radiating Surface on Different Floors Supplied by 
Pipes of Different Sizes 


Size of 


Square Feet of Radiating Surface 



1st Story 

2d Story 

3d Story 

4th Story 

5th Story.. 

6th Story 

1 in. 

30 

55 

65 

75 

85 

95 

ix “ 

60 

90 

110 

125 

140 

160 

l X “ 

100 

140 

165 

185 

210 

240 

2 “ 

200 

275 

375 

425 

500 


2 X “ 

350 

475 





3 “ 

550 






3 X“ 

850 







Table XXVI gives the number of square feet of direct radiation 


which different sizes of mains and branches will supply for varying 
lengths of run. 

7 1 able XXVI may be used for all horizontal mains. For vertical 


risers or drops, Table XXVII may be used. This has been com- 












































112 


HEATING AND VENTILATION 


puted for the same difference in temperature as in the case of Table 
XXVI (17 degrees), and gives the square feet of surface which dif¬ 
ferent sizes of pipe will supply on the different floors of a building, 
assuming the height of the stories to be 10 feet. Where a single 
riser is carried to the top of a building to supply the radiators on the 
floors below, by drop pipes, we must first get what is called the average 
elevation of the system before taking its size from the table. This may 
be illustrated by means of a diagram (see Fig. 105). 

In A we have a riser carried to the third story, and from there a 
drop brought down to supply a radiator on the first floor. The 
elevation available for producing a flow in the riser is only 10 feet, 
the same as though it extended only to the radiator. The water in 
the two pipes above the radiator is practically at the same temperature, 
and therefore in equilibrium, and has no effect on the flow of the 
water in the riser. (Actually there would be some radiation from the 
pipes, and the return, above the radiator, would be slightly cooler, but 
for purposes of illustration this may be neglected). If the radiator 
was on the second floor the elevation of the system would be 20 feet 
(see B); and on the third floor, 30 feet; and so on. The distance 
which the pipe is carried above the first radiator which it supplies 
has but little effect in producing a flow, especially if covered, as it 
should be in practice. Having seen that the flow in the main riser 
depends upon the elevation of the radiators, it is easy to see that the 
way in which it is distributed on the different floors must be con¬ 
sidered. For example, in B, Fig. 105, there will be a more rapid 
flow through the riser with the radiators as shown, than there would 
be if they were reversed and the largest one were placed upon the first 
floor. 

We get the average elevation of the system by multiplying the 
square feet of radiation on each floor by the elevation above the 
heater, then adding these products together and dividing the same 
by the total radiation in the whole system. In the case shown in 
B, the average elevation of the system would be 

(100 X 30) + (50 X 20) + (25 X 10) f 

100 + 50 + 25 ieet; 

and we must proportion the main riser the same as though the whole 
radiation were on the second floor. Looking in Table XXVII, we 
find, for the second story, that a lj-inch pipe will supply 140 square 


122 







HEATING AND VENTILATION 113 

feet; and a 2-inch pipe, 275 feet. Probably a 1^-inch pipe would 
be sufficient. 

Although the height of stories varies in different buildings, 10 
feet will be found sufficiently accurate for ordinary practice. 

INDIRECT HOT=WATER HEATING 

This is used under the same conditions as indirect steam, and 
the heaters used are similar to those already described. Special 


100 



l 1 

25 


A B 

Fig. 105. Diagram to Illustrate Finding of Average Elevation of Heating System. 

attention is given to the form of the sections, in order that there may 
be an even distribution of water through all parts of them. As the 
stacks are placed in the basement of a building, and only a short 
distance above the boiler, extra large pipes must be used to secure a 
proper circulation, for the head producing flow is small. The stack 


123 













































HEATING AND VENTILATION 


114 



casings, cold-air and warm-air pipes, and registers are the same as 
in steam heating. 

Types of Radiators. The radiators for indirect hot-water heating 
are of the same general form as those used for steam. Those shown 
in Figs. 52, 53, 56, 106, and 107 are common patterns. The drum 
'pin, Fig. 106, is an excellent form, as the method of making the 
connections insures a uniform distribution of water through the 
stack. 

Fig. 107 shows a radiator of good form for water circulation, and 
also of good depth, whicn is a necessary point in the design of hot- 
water radiators. They should be not less than 12 or 15 inches deep 
for good results. Box coils of the form given for steam may also be' 



Fig. 106. “Drum Pin” Indirect Hot-Water Radiator. 


used, provided the connections for supply and return are made of 
good size. 

Size of Stacks. As indirect hot-water heaters are used princi¬ 
pally in the warming of dwelling-houses, and in combination with 
direct radiation, the easiest method is to compute the surfaces required 
for direct radiation, and multiply these results by 1.5 for pin radiators 
of good depth. For other forms the factor should vary from 1.5 
to 2, depending upon the depth and proportion of free area for air¬ 
flow between the sections. 

If it is desired to calculate the required surface directly by the 
thermal unit method, we may allow an efficiency of from 360 to 400 
for good types in zero weather. 


124 





HEATING AND VENTILATION 


115 


In schoolhouse and hospital work, where larger volumes of air 
are warmed to lower temperatures, an efficiency as high as 500 B. T. U. 
may be allowed for radiators of good form. 

Flues and Casings. For cleanliness, as well as for obtaining 
the best results, indirect stacks should be hifrig at one side of the 
register or flue receiving the warm air, and the cold-air duct should 
enter beneath the heater at the other side. A space of at least 10 
inches, and preferably 12, should be allowed for the warm air above 
the stack. The top of the casing should pitch upward toward the 
warm-air outlet at least an inch in its length. A space of from 8 to 
10 inches should be allowed for cold air below the stack. 

As the amount of air warmed per square foot of heating surface 
is less than in the case of steam, we may make the flues somewhat 
smaller as compared 
with the size of heater. 

The following p r o - 
portions may be used 
under usual conditions 
for dwelling-houses: 
lj square inches per 
square foot of radia¬ 
tion for the first floor, 

1J square inches for 
the second floor, and 

l £ square inches for Fig. 107. Indirect Hot-Water Radiator. 

the cold-air duct. 

Pipe Connections. In indirect hot-water work, it is not desirable 
to supply more than 80 to 100 square feet of radiation from a single 
connection. When the requirements call for larger stacks, they 
should be divided into two or more groups according to size. 

It is customary to carry up the main from the boiler to a point 
near the basement ceiling, where it is air-vented through a small 
pipe leading to the expansion tank. The various branches should 
grade downward and connect with the tops of the stacks. In this 
way, all air, both from the boiler and from the stacks, will find its way 
to the highest point in the main, and be carried off automatically. 

As an additional precaution, a pet-cock air-valve should be placed 
in the last section of each stack, and brought out through the casing 
by means of a short pipe. 



125 













116 


HEATING AND VENTILATION 


TABLE XXVIII 

Radiating Surface Supplied by Pipes of Various Sizes—Indirect Hot> 
Water System 


Diameter 

Square Feet of Radiating Surface 

Pipe 

100 Ft. Run 

200 Ft. Run 

300 Ft. Run 

400 Ft. Run 

1 in. 

U “ 

15 

30 

25 



H “ * 

50 

40 

25 


2 “ 

100 

75 . 

60 

50 

2i “ 

175 

125 

100 

90 

3 “ 

275 

200 

150 

140 

3i “ 

425 

300 

225 

200 

4 “ 

600 

425 

350 

300 

5 “ 


700 

575 

500 

6 “ 

7 “ 



800 

1,200 


Some engineers make a practice of carrying the main to the 
ceiling of the first story, and then dropping to the basement before 
branching to the stacks, the idea being to accelerate the flow of water 
through the main-, which is liable to be sluggish on account of the 
small difference in elevation between the boiler and stacks. If 
the return leg of the loop is left uncovered, there will be a slight drop 
in temperature, tending to produce this result; but in any case it will 
be exceedingly small. With supply and return mains of suitable 
size and properly graded, there should be no difficulty in securing a 
good circulation in basements of average height. 

Pipe Sizes. As the difference in elevation between the stacks 
and the heater is necessarily small, the pipes should be of ample size 
to offset the slow velocity of flow through them. The sizes mentioned 
in Table XXVIII, for runs up to 400 feet, will be found to supply 
ample radiating surface for ordinary conditions. Some engineers 
make a practice of using somewhat smaller pipes, but the larger sizes 
will in general be found more satisfactory. 


CARE AND MANAGEMENT OF HOT=WATER HEATERS 

The directions given for the care of steam-heating boilers apply 
in a general way to hot-water heaters, as to the methods of caring 
for the fires and for cleaning and filling the heater. Only the special 
points of difference need be considered. Before building the fire, all 
the pipes and radiators must be full of water, and the expansion tank 


126 


















HEATING AND VENTILATION 


117 


should be partially filled as indicated by the gauge-glass. Should 
the water in any of the radiators fail to circulate, see that the valves 
are wide open and that the radiator is free from air. Water must 
always be added at the expansion tank when for any reason it is 
drawn from the system. 

The required temperature of the water will depend upon the 
outside conditions, and only enough fire should be carried to keep 
the rooms comfortably warm. Ther¬ 
mometers should be placed in the flow 
and return pipes near the heater, as a 
guide. Special forms are made for 
this purpose, in which the bulb is im¬ 
mersed in a bath of oil or mercury (see 
Fig. 108). 

FORCED HOT=WATER CIRCU= 

LATION 

While the gravity system of hot- 
water heating is well adapted to 
buildings of small and medium size, 
there is a limit to which it can be car¬ 
ried economically. This is due to the 
slow movement of the water, which 
calls for pipes of excessive size. To 
overcome this difficulty, pumps are 
used to force the water through the 
mains at a comparatively high velocity. 

The water may be heated in a 
boiler in the same manner as for 
gravity circulation, or exhaust steam 
may be utilized in a feed-water heater 
of large size. Sometimes part of the 
heat is derived from an economizer placed in the smoke passage 
from the boilers. 

Systems of Piping. The mains for forced circulation are usually 
run in one of two ways. In the two-pipe system , shown in Fig. 109, 
the supply and return are carried side by side, the former reducing 
in size, and the latter increasing as the branches are taken off. 



Fig. 108. Thermometer Attached to 
Feed-Pipe near Heater, to Deter¬ 
mine Temperature of Water. 


127 















118 


HEATING AND VENTILATION 


The flow through the risers is produced by the difference in 
pressure in the supply and return mains; and as this is greatest 
nearest the pump, it is necessary to place throttle-valves in the risers 
to prevent short-circuiting and to secure an even distribution through 
all parts of the system. 

Fig. 110 shows the single-pipe or circuit system. This is similar 
to the one already described for gravity circulation, except that it can 
be used on a much larger scale. 

A single main is carried entirely around the building in this 
case, the ends being connected with the suction and discharge of the 
pump as shown. 

As the pressure or head in the main drops constantly throughout 
the circuit, from the discharge of the pump back to the suction, it is 


, - H -► *: 

t 

t*. 

_L 

Heate-r 


\ 

rl 

^ Pump 


Fig. 109. “Two-Pipe” System for Forced Hot-Water Circulation. 


evident that if a supply riser be taken off at any point, and the return 
be connected into the main a short distance along the line, there wil 
be a sufficient difference in pressure between the two points to produce 
a circulation through the two risers and the connecting radiators. 
A distance of 8 or 10 feet between the connections is usually ample to 
produce the necessary circulation, and even less if the supply is taken 
from the top of the main and the return connected into the side. 

Sizes of Mains and Branches. As the velocity of flow is inde¬ 
pendent of the temperature and elevation when a pump is used, it is 
necessary to consider only the volume of water to be moved and the 
length of run. 


128 


























HEATING AND VENTILATION 


119 


The volume is found by the equation 


in which 

Q = Gallons of water required per minute; 

R — Square feet of radiating surface to be supplied; 

E = Efficiency of radiating surface in B. T. U. per sq. foot per hour; 

T = Drop in temperature of the water in passing through the heating 
system. 

In systems of this kind, where the circulation is comparatively 
rapid, it is customary to assume a drop in temperature of 30° to 40°, 
between the supply and return. 

Having determined the gallons of water to be moved, the required 
size of main can be found by assuming the velocity of flow, which 
for pipes from 5 to 8 inches in diameter may be taken at 400 to 500 



Pig. 110. “Single-Pipe” or “Circuit” System for Forced Hot-Water Circulation. 


feet per minute. A velocity as high as 600 feet is sometimes allowed 
for pipes of large size, while the velocity in those of smaller diameter 
should be proportionally reduced to 250 or 300 feet for a 3-inch pipe. 
The next step is to find the pressure or head necessary to force the 
water through the main at the given velocity. This in general should 
not exceed 50 or 60 feet, and much better pump efficiencies will be 
obtained with heads not exceeding 35 or 40 feet. 

As the water in a heating system is in a state of equilibrium, the 
only power necessary to produce a circulation is that required to 
overcome the friction in the pipes and radiators; and, as the area of 
the passageways through the latter is usually large in comparison 
with the former, it is customary to consider only the head necessary 
to force the water through the mains, taking into consideration the 
additional friction produced by valves and fittings. 


129 
























120 


HEATING AND VENTILATION 


Each long-tufn elbow may be taken as adding about 4 feet to 
the length of pipe; a short-turn fitting, about 9 feet; 6-mch and 

4- inch swing check-valves, 50 feet and 25 feet, respectively; and 
6-inch and 4-inch globe check-valves, 200 feet and 130 feet, respec¬ 
tively. 

Table XXIX is prepared especially for determining the size of 
mains for different conditions, and is used as follows: 

Example. Suppose that a heating system requires the circulation of 480 
gallons of water per minute through a circuit main 600 feet in length. The 
pipe contains 12 long-turn elbows and 1 swing check-valve. What diameter 
of main should be used ? 

Assuming a velocity of 480 feet per minute as a trial velocity, we 
follow along the line corresponding to that velocity, and find that a 

5- inch pipe will deliver the required volume of water under a head 
of 4.9 feet for each 100 feet length of run. 

The actual length of the main, including the equivalent of the 
fittings as additional length, is 

609 + (12 X 4) + 50 = 698 feet; 

hence the total head required is 4.9 X 6.98 = 34.2 feet. As both 
the assumed velocity and the necessary head come within practicable 
limits, this is the size of pipe which would probably be used. If it 
were desired to reduce the power for running the pump, the size of 
main could be increased. That is, Table XXIX shows that a 6-inch 
pipe would deliver the same volume of water with a friction head of 
only about 2 feet per 100 feet in length, or a total head of 2 X 6.98 — 
15.96, or 16 ft. 

The risers in the circuit system are usually made the same size 
as for gravity work. With double mains, as shown in Fig. 109, they 
may be somewhat smaller, a reduction of one size for diameters over 
1} inches being common 

The branches connecting the risers with the mains may be pro¬ 
portioned from the combined areas of the risers. When the branches 
are of considerable size, the diameter may be computed from the 
available head and volume of water to be moved. 

Pumps. Centrifugal pumps are usually employed in connection 
with forced hot-water circulation, in preference to pumps of the 
piston or plunger type. They are simple in construction, having 
no valves, produce a continuous flow of water, and; for the low heads 


130 


HEATING AND VENTILATION 


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122 


HEATING AND VENTILATION 


against which they are operated, have a good efficiency. A pump of 
this type, with a direct-connected engine, is shown in Fig. 111. 

Under ordinary conditions the efficiency of a centrifugal pump 
falls off considerably for heads above 30 or 35 feet; but special high¬ 
speed pumps are constructed which work with a good efficiency 
against 500 feet or more. 

Under favorable conditions an efficiency of 60 to 70 per cent is 
often obtained; but for hot-water circulation it is more common to 
assume an efficiency of about 50 per cent for the average case. 

The horse-power required for driving a pump is given by the 
following formula: 

H p _HXVX 8.3 
‘ ’ 33,000 X E ’ 

in which 

H = Friction head in feet; 

V = Gallons of water delivered per minute; 

E = Efficiency of pump. 

Centrifugal pumps are made in many sizes and with varying 
proportions, to meet the different requirements of capacity and head. 

Heaters. If the water is heated in a boiler, any good form may 
be used, the same as for gravity work. In case tubular boilers are 
used, the entire shell may be filled with tubes, as no steam space is 
required. 

In order to prevent the water from passing in a direct line from 
the inlet to the outlet, a series of baffle-plates should be used to bring 
it in contact with all parts of the heating surface. 

When steam is used for heating the water, it is customary to 
employ a closed feed-water heater with the steam on the inside of the 
tubes and the water on the outside. 

Any good form of heater can be used for this purpose by providing 
it with steam connections of sufficient size. In the ordinary form of 
heater, the feed-water flows through the tubes, and the connections 
are therefore small, making it necessary to substitute special nozzles 
of large size when used in the manner here described. 

When computing the required amount of heating surface in the 
tubes of a heater, it is customary to assume an efficiency of about 200 
B- T. U. per square foot of surface per hour, per degree difference in 
femperature between the water and .steam. 


132 



HEATING AND VENTILATION 


123 


It is usual to circulate the water at a somewhat higher tempera- 
ture in systems of this kind, and a maximum initial temperature of 
200 degrees, with a drop of 40 degrees in the heating system, may be 
used in computing the size of heater. If exhaust steam is used at 
atmospheric pressure, there will be a difference of 212 — 180 = 32 
degrees, between the average temperature of the water and the steam, 
giving an efficiency of 200 X 32 = 6,400 B. T. U. per square foot 
of heating surface. 

From this it is evident that 6,400 -r- 170 = 38 square feet of 
direct radiating surface, or 6,400 -r 400 = 16 square feet of indirect, 
may be supplied from each square foot of tube surface in the heater. 

Example. A building having 6,000 square feet of direct, and 2,000 
square feet of indirect radiation, is to be warmed by hot water under forced 
circulation. Steam at atmospheric pressure is to be used for heating the 
water. How many square feet of heating surface should the heater contain ? 

6,000 -T- 38 = 158; and 2,000 
16 = 125; therefore, 158 + 

125 = 283 square feet, the area 
of heating surface called for. 

When the exhaust steam is 
not sufficient for the require¬ 
ments, an auxiliary live steam 
heater is used in connection 
with it. 

EXAMPLES FOR PRACTICE 

1. A building contains 
10,000 square feet of direct 
radiation and 4,000 square feet 
of indirect radiation. How 
many gallons of water must be circulated through the mains per min¬ 
ute, allowing a drop in temperature of 40 degrees? Ans. 165 gal. 

2. In the above example, what size of main should be used, 
assuming the circuit to be 300 feet in length and to contain ten long- 
turn elbows? The friction head is not to exceed 10 ft., and the 
velocity of flow not to exceed 300 feet per minute. Ans. 4-inch. 

3. What horse-power will be required to drive a centrifugal 
pump delivering 400 gallons per minute against a friction head of 
40 feet, assuming an efficiency of 50 per cent for the pump? 

Ans. 8 H. P, 



133 





124 


HEATING AND VENTILATION 


4. A building contains 10,000 square feet of direct radiation and 

5,000 square feet of indirect radiation. Steam at atmospheric pres¬ 
sure is to be used. The initial temperature of the water is to be 200°; 
and the final P 160°. How many square feet of heating surface should 
the heater contain? Ans. 575 sq. ft. 

5. How many square feet would be required in the above 

heater (Example 4) if the initial temperature of the water were 180° 
and the final temperature 150°? * Ans. 399 sq. ft. 

EXHAUST=STEAM HEATING 

Steam, after being used in an engine, contains the greater part 
of its heat; and if not condensed or used for other purposes, it can 
usually be employed for heating without affecting to any great extent 
the power of the engine. In general, we may say that it is a matter of 
economy to use the exhaust for heating, although various factor® 
must be considered in each case to determine to what extent this is 
true. The more important considerations bearing upon the matter 
are: the relative quantities of steam required for power and for 
heating; the length of the heating season; the type of engine used; 
the pressure carried; and, finally, whether the plant under con¬ 
sideration is entirely new, or whether, on the other hand, it involves 
the adapting of an old heating system to a new plant. 

The first use to be made of the exhaust steam is the heating of 
the feed-water, as this effects a constant saving both summer and 
winter, and can be done without materially increasing the back¬ 
pressure on the engine. Under ordinary conditions, about one-sixth 
of the steam supplied to the engine can be used in this way, or more 
nearly one-fifth of the exhaust discharged from the engine. 

We may assume in average practice that about 80 per cent of 
the steam supplied to an engine is discharged in the form of steam 
at a lower pressure, the remaining 20 per cent being partly converted 
into work and partly lost through cylinder condensation. Taking 
this into account, there remains, after deducting the steam used fot 
feed-water heating, .8 X j = .64 of the entire quantity of steam 
supplied to the engine, available for heating purposes. 

When the quantity of steam required for heating is small com¬ 
pared with the total amount supplied to the engine, or where the 
heating season is short, it is often more economical to run the engine 


134 



HEATING AND VENTILATION 


125 


condensing and use the live steam for heating. This can be deter¬ 
mined in any particular case by computing the saving in fuel by the 
use of a condenser, taking into account the interest and depreciation 
on the first cost of the condensing apparatus, and the cost of water, 
if it must be purchased, and comparing it with the cost of heating 
with live steam. 

Usually, however, in the case of office buildings and institutions, 
and commonly in the case of shops and factories, especially in north¬ 
erly latitudes, it is advantageous to use the'exhaust for heating, even if 
a condenser is installed for summer use only. The principal objec¬ 
tion raised to the use of exhaust steam has been the higher back¬ 
pressure required on the engines, resulting in a loss of power nearly 
proportional to the ratio of the back-pressure to the mean effective 
pressure. There are two ways of offsetting this loss—one, by raising 
the initial or boiler pressure; and the other, by increasing the cut- 
. off of the engine. Engines are usually designed to work most econom¬ 
ically at a given cut-off, so that in most cases it is undesirable to 
change it to any extent. Raising the boiler pressure, on the other 
hand, is not so objectionable if the increase amounts to only a few 
pounds. 

Under ordinary conditions in the case of a simple engine, a rise 
of 3 pounds in the back-pressure calls for an increase of about 5 
pounds in the boiler pressure, to maintain the same power at the 
engine. 

The indicator card shows a back-pressure of about 2 pounds 
when an engine is exhausting into the atmosphere, so that an increase 
of 3 pounds would bring the pressure up to a total of 5 pounds which 
should be more than sufficient to circulate the steam through any 
well-designed heating system. 

If it is desired to reduce rather than increase the back-pressure, 
one of the so-called vacuum systems , described later, can be used. 

The systems of steam heating which have been described are 
those in which the water of condensation flows back into the boiler 
by gravity. Where exhaust steam is used, the pressure is much below 
that of the boiler, and it must be returned either by a pump or by a 
return trap. The exhaust steam is often insufficient to supply the 
entire heating system, and must be supplemented by live steam taken 
directly from the boiler. This must first pass through a reducing 


135 


126 


HEATING AND VENTILATION 


valve in order to reduce the pressure to correspond with that carried 
in the heating system. 

An engine does not deliver steam continuously, but at regular 
intervals, at the end of each stroke; and the amount is likely to vary 
with the work done, since the governor is adjusted to admit steam in 
such a quantity as is required to maintain a uniform speed. If the 
work is light, very little steam will be admitted to the engine; and 
for this reason the supply available for heating may vary somewhat, 
depending upon the use made of the power delivered by the engine. 
In mills the . amount of exhaust steam is practically constant; in 
office buildings where power is used for lighting, the variation is 
greater, especially if power is also required for the running of elevators. 

The general requirements for a successful system of exhaust 
steam heating include a system of piping of such proportions that 
only a slight increase in back-pressure will be thrown upon the engine; 
a connection which shall automatically supply live steam at a reduced 
pressure as needed; provision for removing the oil from the exhaust 
steam; a relief or back-pressure valve arranged to prevent any sudden 
increase in back pressure on the engine; and a return system of some 
kind for returning the water of condensation to the boiler against 
a higher pressure. These requirements may be met in various ways, 
depending upon actual conditions found in different cases. 

To prevent sudden changes in the back-pressure, due to irregular 
supply of steam, the exhaust pipe from the engine is often carried to 
a closed tank having a capacity from 30 to 40 times that of the engine 
cylinder. This tank may be provided with baffle-plates or other 
arrangements and may serve as a separator for removing the oil from 
the steam as it passes through. 

Any system of piping may be used; but great care should be 
taken that as little resistance as possible is introduced at bends and 
fittings; and the mains and branches should be of ample size. Usually 
the best results are obtained from the system in which the main steam 
pipe is carried directly to the top of the building, the distributing pipes 
being run from that point, and the radiating surfaces supplied by a 
down-flowing current of steam. 

Before taking up the matter of piping in detail a few of the more 
important pieces of apparatus will be described in a brief way. 

Reducing Valves. The action of pressure-reducing valves has 


136 


HEATING AND VENTILATION 


127 


been taken up quite fully in “Boiler Accessories,” and need not be 
repeated here. When the reduction in pressure is large, as in the 
case of a combined power and heating plant, the valve may be one or 
two sizes smaller than the low-pressure main into which it discharges. 
For example, a 5-inch valve will supply an 8-inch main, a 4-inch a 
6-inch main, a 3-inch a 5-inch main, a 2^-inch a 4-inch main, etc. 

For the smaller sizes, the difference should not be more than one 
size. All reducing valves should be provided with a valved by-pass 
for cutting out the valve in case of repairs. This connection is usually 
made as shown in plan by Fig. 112. 

Grease Extractor. When exhaust steam is used for heating pur¬ 
poses, it must first be passed through some form of separator for 
removing the oil; and as an additional precaution it is well to pass the 



BY-PASS 


Fig-112. Connections of Reducing Valve in Exhaust-Steam Heating System. 

water of condensation through a separating tank before returning it to 
the boilers. 

Such an arrangement is shown in Fig. 113. As the oil collects 
on the surface of the water in the tank, it can be made to overflow 
’nto the sewer by closing the valve in the connection with the receiving 
tank, for a short time. 

As much of the oil as possible should be removed before the 
steam enters the pipes and radiators, else a coating will be formed on 
their inner surfaces, which will -reduce their heating efficiency. The 
separation of the oil is usually effected by introducing a series of 
baffling plates in the path of the steam; the particles of oil striking 
these are stopped, and thus separated from the steam. The oil drops 
into a receiver provided for this purpose and is discharged through a 
trap to the sewer. 

In the separator, or extractor, shown in Fig. 114, the separation is 
accomplished by a series of plates placed in a vertical position in thf 


137 























128 


HEATING AND VENTILATION 


body of the separator, through which the steam must pass. These 
plates consist of upright hollow columns, with openings at regular 
intervals for the admission of water and oil, which drain downward 
to the receiver below. The steam takes a zigzag course, and all of 
it comes in contact with the intercepting plates, which insures a 
thorough separation of the oil and other solid matter from the steam. 
Another form, shown in Fig. 115, gives excellent results, and has the 
advantage of providing an equalizing chamber for overcoming, to 
some extent, the unequal pressure due to the varying load on the 
engine. It consists of a tank or receiver about 4 feet in diameter, 
with heavy boiler-iron heads slightly crowned to give stiffness. 



Fig. 113. Separator for Removing Oil from Exhaust Steam and Water Condensation. 

Through the center is a layer of excelsior (wooden shavings of long 
fibre) about 12 inches in thickness, supported on an iron grating, 
with a similar grating laid over the top to hold it in place. The 
steam enters the space below the excelsior and passes upward, as 
shown by the arrows. The oil is caught by the excelsior, which can 
be renewed from time to time as it becomes saturated. The oil and 
water which fall to the bottom of the receiver are carried off through 
a trap. Live steam may be admitted through a reducing valve, for 
supplementing the exhaust when necessary. 

Back=Pressure Valve. This is a form of relief valve which is 
placed in the outboard exhaust pipe to prevent the pressure in the 
heating system from rising above a given point. Its office is the 


138 


















HEATING AND VENTILATION 


129 


reverse of the reducing valve, which supplies more steam when 
the pressure becomes too low. The form shown in Fig. 116 is 
designed for a vertical pipe. The valve proper consists of two discs 
of unequal area, the combined area of which equals that of the pipe. 
The force tending to open the valve is that due to the steam pressure 
acting on an area equal to the difference in area between the two discs; 
it is clear from the cut that the 
pressure acting on the larger 
disc tends to open the valve 
while the pressure on the smal¬ 
ler acts in the opposite direc¬ 
tion. The valve-stem is con¬ 
nected by a link and crank 
arm with a spindle upon which 
is a lever and weight outside. 

As the valve opens, the weight 
is raised, so that, by placing it 
in different positions on the 
lever arm, the valve will open 
at any desired pressure. 

Fig. 117 shows a different 
type, in which a spring is used 
instead of a weight. This 
' valve has a single disc moving 
in a vertical direction. The 
valve stem is in the form of a 
piston or dash-pot which pre¬ 
vents a too sudden movement 
and makes it more quiet in 
its action. The disc is held 
on its seat against the steam 
pressure by a lever attached 
to the spring as shown. When 
the pressure of the steam on the underside becomes greater than the 
tension of the spring, the valve lifts and allows the steam to escape. 
The tension of the spring can be varied by means of the adjusting 
screw at its upper end. 

A back-pressure valve is simply a low-pressure safety-valve 



RECEIVER 


DISCHARGE 


Fig. 114. Oil Separator Consisting 
Plates with Openings Giving £ 
Zigzag Course. 


of Vertical 
team a 


139 



















































130 


HEATING AND VENTILATION 


designed with a specially large opening for the passage of steam 
through it. These valves are made for horizontal as .well as for 
vertical pipes. 



Exhaust Head. This is a form of separator placed at the top 
of an outboard exhaust pipe to prevent the water carried up in the 
steam from falling upon the roofs of buildings or in the street below. 
Fig. 118 is known as a centrifugal exhaust head. The steam, on 

entering at the bottom, is given a 
whirling or rotary motion by the 
spiral deflectors; and the water is 
thrown outward by centrifugal force 
against the sides of the chamber, from 
which it flows into the shallow trough 
at the base, and is carried away through 
the drip-pipe, which is brought down 
and connected with a drain-pipe in¬ 
side the building. The passage of the 
steam outboard is shown by the arrows. 
Other forms are used in which the 
water is separated from the steam by 
deflectors which change the direction of 
the currents. 



Fig. 116. Automatically Acting Back- 
Pressure Valve Attached to Ver¬ 
tical Pipe. For Preventing 
Rise of Pressure in System 
above any Desired 
Point. 


Automatic Return=Pumps. In exhaust heating plants, the 
condensation is returned to the boilers by means of some form of 
return-pump. A combined pump and receiver of the form illus- 


140 






















HEATING AND VENTILATION 


131 


trated in Fig. 119 is generally used. This consists of a cast-iron or 
wrought-iron- tank mounted on a base in connection with a boiler 
feed-pump. Inside the tank is a ball-float connected by means of 
levers with a valve in the steam pipe which is connected with the 
pump When the water-line in the tank rises above a certain level, 
the float is raised and opens the steam valve, which starts the pump. 
When the water is lowered to its normal level, the valve closes and 
the pump stops. By this arrangement, a constant water-line is 
maintained in the receiver, and the pump runs only as needed to care 
for the condensation as it returns from the heating system. If dry 
returns are used, they may be brought together and connected with 
the top of the receiver. If it is desired to seal the horizontal runs, as 




Fig. 117. Back-Pressure Valve Automatic- Fig. 118. Centrifugal Exhaust Head, 
ally Operated by a Spring. 

is usually the case, the receiver may be raised to a height sufficient 
to give the required elevation and the returns connected near the 
bottom below the water-line. 

A balance-pipe, so called, should connect the heating main with 
the top of the tank, for equalizing the pressure; otherwise the steam 
above the water would condense, and the vacuum thus formed would 
draw all the water into the tank, leaving the returns practically empty 
and thus destroying the condition sought. Sometimes an inde¬ 
pendent regulator or pump governor is used in place of a receive?. 
One type is shown in Fig.. 120. The return main is connected at 


141 




























132 


HEATING AND VENTILATION 


the upper opening, and the pump suction at the lower. A float inside 
the chamber operates the steam valve shown at the top, and the pump 
works automatically as in the case just described. 

If it is desired to raise the water-line, the regulator may be 
elevated to the desired height and connections made as shown in 

Fig. 121. 

Return Traps. The principle of the return trap has been de¬ 
scribed in “Boiler Accessories,” but its practical form and application 



Fig. 119. Buffalo Duplex Automatic Feed Pump and Receiver for Returning Water of 
Condensation to Boiler. 

Courtesy of Buffalo Forge Company, Buffalo, New York. 

will be taken up here. The type shown in Fig. 122 has all its working 
parts outside the trap. It consists of a cast-iron bowl pivoted at G and 
II. There is an opening through G connecting with the inside of 
the bowl. The pipe K connects through C with an interior pipe 
opening near the top (see Fig. 123). The pipe D connects with a 
receiver, into which all the returns are brought. A is a check-valve 
allowing water to pass through in the direction shown by the arrow e 
E is a pipe connecting with the boiler below the water-line. B is a 


142 










HEATING AND VENTILATION 


133 


check opening toward the boiler, and K, a pipe connected with the 
steam main or drum. 

The action of the trap is as fol¬ 
lows : As the bowl fills with water from 
the receiver, it overbalances the 
weighted lever and drops to the bot¬ 
tom of the ring. This opens the valve 
C,' and admits steam at boiler pres¬ 
sure to the top of the trap. Being at 
a higher level the water flows by grav¬ 
ity into the boiler, through the pipe E. 

Water and steam are kept from passing 
out through D by the check A . 

When the trap has emptied it¬ 
self, the weight of the ball raises it 
to the original position, which movement closes the valve C and opens 
the small vent F. The pressure in the bowl being relieved, water 
flows in from the receiver through D, until the trap is filled, when the 



Fig. 120. Automatic Float-Operated 
Pump Governor Used instead 
of a Receiver. 


STEAM 


AUTOMA T/C VALVE 

J 


TO PUMP 


V/A TER L/A/E 



Q 


TO PUMP 


Fig. 121. Pump Regulator Placed at Sufficient Height to Raise Water-Line to 
Point Desired. 

process is repeated. In order to work satisfactorily, the trap should 
be placed at least 3 feet above the water-level in. the boiler, and the 


143 


i 












































134 


HEATING AND VENTILATION 




pressure in the returns must always be sufficient to raise the water 
from the receiver to the trap against atmospheric pressure, which is 
theoretically about 1 pound for every 2 feet in height. In practice 
there will be more or less friction to 
.overcome, and suitable adjustments must 
be made for each particular case. 

Fig. 124 shows another form of trap 
acting upon the same principle, exeept 
that in this case the steam valve is oper¬ 
ated by a bucket or float inside the trap. 

The pipe connections are practically the 
same as with the trap just described. 

Return traps are more commonly 
used in smaller plants where it is desired Fig . 123 . Return Trap with work- 
to avoid the expense and care of a pump. ing Parts External * 

Damper=Regulators. Every heating and every power plant 
should be provided with automatic means for closing the dampers 
when the steam pressure reaches a certain point, and for opening 
them again when the pressure drops. There are various regulators 
designed for this purpose, a simple form of which is shown in Fig. 125. 

Steam at boiler pres¬ 


sure is admitted beneath a 
diaphragm which is bal¬ 
anced by a weighted lever. 
When the pressure rises to a 
certain point, it raises the 
lever slightly and opens a 
valve which admits water 
under pressure above a dia¬ 
phragm located near the 
smoke-pipe. This action 
forces down a lever con¬ 
nected by chains with the 


Fig. 123. Showing Interior Detail of Return Trap 
of Fig. 122. 


damper, and closes it 


When the steam pressure 
drops, the water-valve is closed, and the different parts of the 
apparatus take their original positions. 

Another form similar in principle is shown in Fig. 126. In this 


144 







HEATING AND VENTILATION 135 

case a piston is operated by the water-pressure, instead of a diaphragm. 
In both types the pressures at which the damper shall open and close 
are regulated by suitable adjustments'of the weights upon the levers 
Pipe Connections. The method of making the pipe connections 
in any particular case will depend upon the general arrangement 
ot the apparatus and the various conditions. Fig. 127 illustrates 



the general principles to be followed, and by suitable changes may be 
used as a guide in the design of new systems. 

Steam first passes from the boilers into a large drum or header. 
From this, a main, provided with a shut-off valve, is taken as shown; 
one branch is carried to the engines, while another is connected with 
the heating system through a reducing valve having a by-pass and 
Eut-out valves. The exhaust from the engines connects with the large 
main over the boilers at a point just above the steam drum. The 


145 









































136 


HEATING AND VENTILATION 


branch at the right is carried outboard through a back-pressure 
valve which may be set to carry any desired pressure on the system. 
The other branch at the left passes through an oil separator into the 
heating system. The connections between the mains and radiators 
are made in the usual way, and the main return is carried back to the 
return pump near the floor. A false water-line or seal is obtained by 
elevating the pump regulator as already described. An equalizing 



Fig. 125. Simple Form of Automatic Damper-Regulator, Operated by Lever Attached to 
Diaphragm, for Closing Dampers when Steam Pressure Reaches a Certain Point. 


or balance pipe connects the top of the regulator with the low-pressure 
heating main, and high pressure is supplied to the pump as shown. 

A sight-feed lubricator should be placed in this pipe above the 
automatic valve; and a valved by-pass should be placed around the 
regulator, for running the pump in case of accident or repairs. The 
oil separator should be drained through a special oil trap to a catch- 
basin or to the sewer; and the steam drum or any other low points 


146 


































HEATING AND VENTILATION 


137 


or pockets in the high-pressure piping should be dripped to the 
return tank through suitable traps. 

Means should be provided for draining all parts of the system 
to the sewer, and all traps and special apparatus should be by-passed. 
The return-pump should always be duplicated in a plant of any size, 
as a safeguard against accident; and the two pumps should be run 
alternately, to make sure that one is always in working order. 



One piece of apparatus not shown in Fig. 127 is the feed-water 
heater. If all of the exhaust steam can be utilized for heating pur¬ 
poses, this is not necessary, as the cold water for feeding the boilers 
may be discharged into the return pipe and be pumped in with the 
condensation. In summertime, however, when the heating plant is 
nst in use, a feed-water hearer is necessary, as a large amount of heat 


147 































































138 HEATING AND VENTILATION 



148 


Fig. 127. General Method of Making Pipe Connections for Exhaust-Steam Heating. 































































































































HEATING AND VENTILATION 


139 


which would otherwise be wasted may be saved in this way. The 
connections will depend somewhat upon the form of heater used; 
but in general a single connection with the heating main inside the 
back-pressure valve is all that is necessary. The condensation from 
the heater should be trapped to the sewer. 


149 



VACUUM PUMP INSTALLATION IN WEST JERSEY HOMEOPATHIC HOSPITAL 
SHOWING WEBSTER SUCTION STRAINER, VACUUM GOVERNOR, AND GAGES 

Courtesy of Warren Webster and Company, Camden, New Jersey 













HEATING AND VENTILATION 

PART III 


VACUUM SYSTEMS 

Low=Pressure or Vacuum Systems. In the systems of steam 
heating which have been described up to this point, the pressure 
carried has always been above that of the atmosphere, and the action 
of gravity has been depended upon to carry the water of condensation 
back to the boiler or receiver; the air in the radiators has been forced 
out through air-valves by the pressure of steam back of it. Methods 
will now be taken up in which the pressure in the heating system is 
less than the atmosphere, and where 
the circulation through the radiators is 
produced by suction rather than by 
pressure. Systems of this kind have 
several advantages over the ordinary 
methods of circulation under pressure. 

First —no back-pressure is produced 
at the engines when used in connection 
with exhaust steam; but rather there 
will be a reduction of pressure due to 
the partial vacuum existing in the radia¬ 
tors. Second — there is a complete 
removal of air from the coils and 
radiators, so that all portions are 
steam-filled and available for heating 
purposes. Third —there is complete rainage through the returns, 
especially those having long horizontal runs; and there is absence of 
water-hammer. Fourth — smaller return pipes may be used. 
The two older systems of this kind in common use are known as the 
Webster and Paul systems; other systems of recent introduction are 
described in the Instruction Paper on Steam and Hot-Water Fitting. 

Webster System. This consists primarily of an automatic outlet- 
valve on each coil and radiator, connected with some form of suction 
apparatus such as a pump or ejector. One type of valve used is 



Fig. 128. Webster Air Outlet-Valve for 
Radiator. 

Courtesy of Warren Webster and 
Company, Camden, New Jersey . 


151 








142 


HEATING AND VENTILATION 


shown in section in Fig. 128, which replaces the usual hand-valve at 
the return end of the radiator. It is similar in construction to some 
of the air-valves already described, consisting of a bellows or sylphon 
which is filled with a volatile liquid; in 
the presence of the steam the liquid 
partially vaporizes, thus expanding the 
bellows so that it presses against the 
valve opening and closes it. When water 
or air fills the valve, the bellows con¬ 
tracts and allows it to be sucked out as 
shown by the arrows. 

Fig. 129 shows a thermostatic valve, 
which operates on the same principle as 
that of Fig. 128, but which is designed for 
higher pressures than are commonly used 
for heating purposes; and Fig. 130 indicates 
the method used in draining the bottoms of risers or the ends of mains. 

Fig. 131 shows another form of this valve, called a water-seal 
motor, which is used under practically the same conditions. Its 
action is as follows: 

Ordinarily, the seal A is down, and the central tube-valve is 
resting upon the seat, closing the port K and preventing direct com¬ 
munication between the interior of 
the motor-body E and the outlet 
L. The outlet is attached to a pipe 
leading to a vacuum-pump, or 
other draining apparatus, which 
exhausts the space F above the seal 
through the annular space between 
the spindle B and the inside of the 
Dr-op Le^ central tube G. The water of 

Fig. 130. Showing Method of Draining j ,• * 

Bottoms of Risers or Ends condensation, accumulating m the 

of Mains. ,. A .. ? 

radiator or coil, passes into the 
chamber E, through the inlet C, rises in the chamber, and seals the 
space between the seal-shell A and the sleeve of the bonnet D. The 
differential pressure thus created causes the seal A to rise, lifting the 
end of the central tube off the seat, thus opening a clear passageway 
for the ejection of the water of condensation. 




Fig. 129. Webster Thermostat 
for High-Pressure Work. 
Courtesy of Warren Webster 
and Company, Camden, 
New Jersey. 


152 



















HEATING AND VENTILATION 


143 



Fig. 131. Water-Seal Motor. 

form a passageway through which the air is continually withdrawn by 
the vacuum pump or other draining apparatus. 

The action outlined continues as long as water is present. 

No adjustment whatever is necessary; the motor is entirely auto¬ 
matic. 

One special advantage claimed for this system is that the amount 
of steam admitted to the radiators may be regulated to suit the require¬ 
ments of outside temperature; and is possible without wate”- 


When all the water of condensation has been drawn out of the 
radiator, the seal and tube are reseated by gravity, thus closing the 
port K, preventing waste or loss of steam; and the pressure is equal¬ 
ized above and below the seal because of the absence of water. This 
action is practically instantaneous. When the condensation is small 
in quantity, the discharge is intermittent and rapid. 

The space between the seal A and the sleeve of the bonnet D, 
and the annular space between the central tube G and the spindle B, 


153 









































154 












































































































































































HEATING AND VENTILATION 


145 


logging or hammering. This may be done at will by closing down on 
the inlet supply to the desired degree. The result is the admission 
of a smaller amount of steam to the radiator than it is calculated to 
condense normally. The condensation is removed as fast as formed, 
by the opening of the thermostatic valve. 

The general application of this system to exhaust heating is 
shown in Fig. 132. Exhaust steam is brought from the engine as 
shown, one branch leads outboard through a back-pressure valve, 
while the other connects with the heating system through a grease 
extractor. A live steam connection is made through a reducing 
valve, as in the ordinary system. Valved connections are made 
with the coils and radiators in the usual manner; but the return 
valves are replaced by the special thermostatic valves described 
above. 

The main return is brought down to a vacuum pump which dis¬ 
charges into a return tank (not shown in the cut), where the air is 
separated from the water and passes off through a vapor pipe at the 
top. The condensation then flows into the feed-water heater, or 
receiving tank, from which it is automatically pumped back into the 
boilers. The cold-water feed supply is connected with the return 
tank, and a small cold-water jet is connected into the suction at the 
vacuum pump for increasing the vacuum in the heating system by 
the condensation of steam at this point. 

Paul System. In this system the suction is connected with the 
air-valves instead of the returns, and the vacuum is produced by 
means of a steam ejector instead of a pump. The returns are carried 
back to a receiving tank, and pumped back to the boiler in the usual 
manner. The ejector in this case is called the exhauster. 

Fig. 133 shows the general method of making the pipe connec¬ 
tions with the radiators in this system; and Fig. 134, the details of 
connection at the exhauster. 

A A are the returns from the air-valves, and connect with the 
exhausters as shown. Live steam is admitted in small quantities 
through the valves BB; and the mixture of air and steam is discharged 
outboard through the pipe C . D D are gauges showing the pressure 
in the system; and E E are check-valves. The advantage of this 
system depends principally upon the quick removal of air from the 
various radiators and pipes, which constitutes the principal obstruction 


155 


146 


HEATING AND VENTILATION 


to circulation; the inductive action in many cases is sufficient to cause 
the system to operate somewhat below atmospheric pressure. 

Where exhaust steam is used for heating, the radiators should 



be somewhat increased in size, owing to the lower temperature of 
the steam. It is common practice to add from 20 to 30 per cent to 
the sizes required for low-pressure live steam. 


156 








































HEATING AND VENTILATION 


147 


FORCED BLAST 

In a system of forced circulation by means of a fan or blower 
the action is positive and practically constant under all usual con¬ 
ditions of outside temperature and wind action. This gives it a 
decided advantage over natural or gravity methods, which are af- 



Fig. 134. Details of Connections at Exhauster, Paul System. 


fected to a greater or less degree by changes in wind-pressure, and 
makes it especially adapted to the ventilation and warming of large 
buildings such as shops, factories, schools, churches, halls, theaters, 
etc., where large and definite air-quantities are required. 

Exhaust Method. This consists in drawing the air out of a 
building, and providing for the heat thus carried away by placing 


157 
































































148 


HEATING AND VENTILATION 


steam coils under windows or in other positions where the inward 
leakage is supposed to be the greatest. When this method is used, a 
partial vacuum is created within the building or room, and all currents 
and leaks are inward; there is nothing to govern definitely the quality 
and place of introduction of the air, and it is difficult to provide suit¬ 
able means for warming it. 

Plenum Method. In this case the air is forced into the building, 
and its quality, temperature, and point of admission are completely 
under control. All spaces are filled with air under a slight pressure, 
and the leakage is outward, thus preventing the drawing of foul air 
into the room from any outside source. But above all, ample oppor¬ 
tunity is given for properly warming the air by means of heaters, 
either in direct connection with the fan or in separate passages leading 
to the various rooms. 

Form of Heating Surface. The best type of heater for any 
particular case will depend upon the volume and final temperature 
of the air, the steam pressure, and the available space. When the 
air is to be heated to a high temperature for both warming and venti¬ 
lating a building, as in the case of a shop or mill, heaters of the general 
form shown in Figs. 135, 136, and 137 are used. These may also be 
adapted to all classes of work by varying the proportions as required. 
They can be made shallow and of large superficial area, for the com¬ 
paratively low temperatures used in purely ventilating work; or 
deeper, with less height and breadth, as higher temperatures are 
required. 

Fig. 135 shows in section a heater of this type, and illustrates 
the circulation of steam through it. It consists of sectional cast-iron 
bases with loops of wrought-iron pipe connected as shown. The 
steam enters the upper part of the bases or headers, and passes up 
one side of the loops, then across the top and down on the other side, 
where the condensation is taken off through the return drip, which 
is separated from the inlet by a partition. These heaters are made 
up in sections of 2 and 4 rows of pipes each. The height varies from 
3} to 9 feet, and the width from 3 feet to 7 feet in the standard sizes. 
They are usually made up of 1-inch pipe, although lj-inch is commonly 
used in the larger sizes. Fig. 136 shows another form; in this case 
all the loops are made of practically the same length by the special 
form of construction shown. This is claimed to prevent the short- 


158 


HEATING AND VENTILATION 


149 


circuiting of steam through the shorter loops, which causes the outer 
pipes to remain cold. Both of these heaters are usually encased in a 



sheet-steel housing, but may be supported on a foundation between 
brick walls if desired. Another form of heater used in the same 
manner as the above is shown in Fig. 137. 


159 






























































150 


HEATING AND VENTILATION 


Fig. 138 shows a special form of heater particularly adapted to 
ventilating work where the air does not have to be raised above 70 or 
80 degrees. It is made up of 1-inch wrought-iron pipe connected 



with supply and return headers; each section contains 14 pipes, and 
they are usually made up in groups of 5 sections each. These coils 
are supported upon tee-irons resting upon a brick foundation. Heat- 


160 

















HEATING AND VENTILATION 


151 


ers of this form are usually made to extend across the side of a room 
with brick walls at the sides, instead of being encased in steel housings. 

Fig. 139 shows a front view of a cast-iron sectional heater for 
use under the same conditions as the pipe heaters already described. 
This heater is made up of several banks of sections, like the one shown 
in the cut, and enclosed in a steel-plate casing. 

Cast-iron indirect radiators of the pin type are well adapted for 
use in connection with mechanical ventilation, and also for heating 



Fig. 137. Miter Hot-Blast Heatei without Casing or Connections. 

Courtesy of Buffalo Forge Company , Buffalo , New York. 

where the air-volume is large and the temperature not too high, as 
in churches and halls. They make a convenient form of heater for 
schoolhouse and similar work, for, being shallow, they can be sup¬ 
ported upon I-beams at such an elevation that the condensation will be 
returned to the boilers by gravity. 

In the case of vertical pipe heaters, the bases are below the water¬ 
line of the boilers, and the condensation must be returned by the use 
of pumps and traps. 


161 





































152 


HEATING AND VENTILATION 


Efficiency of Pipe Heaters. The efficiency of the heaters used in 
connection with forced blast varies greatly, depending upon the 
temperature of the entering air, its velocity between the pipes, the 
temperature to which it is raised, and the steam pressure carried in 
the heater. The general method in which the heater is made up is 
also an important factor. 

In designing a heater of this kind, care must be taken that the 
free area between the pipes is not contracted to such an extent that 
an excessive velocity will be required to pass the given quantity of 


CE/L/Nl7 L/NE 




Fig. 138. Heater Especially Adapted to Ventilation where Air does not Have to he Heated 
above 70 to 80 degrees F. 

air through it. In ordinary work it is customary to assume a velocity 
of 800 to 1,000 feet per minute; higher velocities call for a greater 
pressure on the fan, which is not desirable in ventilating work. 

In the heaters shown, about .4 of the total area is free for the 
passage of air; that is, a heater 5 feet wide and 6 feet high would 
have a total area of 5 X 6 = 30 square feet, and a free area between 
the pipes of 30 X .4 = 12 square feet. The depth or number of rows 
of pipe does not affect the free area, although the friction is increased 
and additional work is thrown upon the fan. The efficiency in any 


162 




























































HEATING ANI) VENTILATION 


153 


given heater will be increased by increasing the velocity of the air 
through it; but the final temperature will be diminished; that is, 
a larger quantity of air will be heated to a lower temperature in the 
second case, and, while the total heat given off is greater, the air- 
quantity increases more rapidly than the heat-quantity, which causes 
a drop in temperature. 

Increasing the number of rows of pipe in a heater, with a con¬ 
stant air-quantity, increases the final temperature of the air, but 
diminishes the efficiency of the heater, because the average difference 
in temperature between the air and the steam is less. Increasing 
the steam pressure in the 


I < 4 : m i 



heater (and consequently its 
temperature) increases both 
the final temperature of the 
air and the efficiency of the 
heater. Table XXX has been 
prepared from different tests, 
and may be used as a guide 
in computing probable results 
under ordinary working con¬ 
ditions. In this table it is 
assumed that the air enters 
the heater at a temperature of 
zero and passes between the 
pipes with a velocity of 800 
feet per minute. Column 1 
gives the number of rows of 
pipe in the heater, ranging 
from 4 to 20 rows; and columns 2, 3, and 4, show the final tempera¬ 
ture to which the entering air will be raised from zero under various 
pressures. Under 5 pounds pressure, for example, the rise in tem¬ 
perature ranges from 30 to 140 degrees; under 20 pounds, 35 to 150 
degrees; and under 60 pounds, 45 to 170 degrees. Columns 5,6, and 
7 give approximately the corresponding efficiency of the heater. For 
example, air passing through a heater 10 pipes deep and carrying 20 
pounds pressure, will be raised to a temperature of 90 degrees, and 
the heater will have an efficiency of 1,650 B. T. U. per square foot of 
^surface per hour. 


Fig. 139. Front View of Cast-Iron Sectional 
Heater. The Banks of Sections are En¬ 
closed in a Steel-Plate Casing. 


163 












154 


HEATING AND VENTILATION 


TABLE XXX 

Data Concerning Pipe Heaters 

Temperature of entering air, zero.—Velocity of air between the pipes, 
800 feet per minute. 


Rows op 
Pipe Deep 

Temperature to which Air will 
be Raised from Zero 

Efficiency of Heating Surface inB.T.U., 
per Square Foot per Hour 

Steam Pressure in Heater 

Steam Pressure in Heater 


5 lbs. 

20 lbs. 

60 lbs. 

5 lbs. 

20 lbs. 

60 lbs. 

4 

30 

35 

45 

1,600 

1,800 

2,000 

6 

50 

55 

65 

1,600 

1,800 

2,000 

8 

65 

70 

85 

1,500 

1,650 

1,850 

10 

80 

90 

105 

1,500 

1,650 

1,850 

12 

95 

105 

125 

1,500 

1,650 

1,850 

14 

105 

120 

140 

1,400 

1,500 

1,700 

16 

120 

130 

150 

1,400 

1,500 

1,700 

18 

130 

140 

160 

1,300 

1,400 

1,600 

20 

140 

150 

170 

1,300 

1,400 

1,600 


For a velocity of 1,000 feet, multiply the temperatures given in 
the table by .9, and the efficiencies by 1.1. 

Example. How many square feet of radiation will be required to raise 
600,000 cubic feet of air per hour from zero to 80 degrees, with a velocity 
through the heater of 800 feet per minute and a steam pressure of 5 pounds? 
What must be the total area of the heater front, and how many, rows of 
pipes must it have? 

Referring back to the formula for heat required for ventilation, 
we have 


600,000 X 80 
55 


872,727 B. T. U. required. 


Referring to Table XXX, we find that for the above conditions a 
heater 10 pipes deep is required, and that an efficiency of 1,500 

872 727 

B. T. U. will be obtained. Then J - = 582 square feet of 

1,500 

surface required, which may be taken as 600 in round numbers 

600,000 _ jq qoq cu bi c feet of air per minute; and = 12.5 

60 r 800 

square feet of free area required through the heater. If we assume 

.4 of the total heater front to be free for the passage of air, then 

12 5 

—— = 31 square feet, the total area required. 


164 

































HEATING AND VENTILATION 


155 


For convenience in estimating the approximate dimensions of 
a heater, Table XXXI is given. The standard heaters made by dif¬ 
ferent manufacturers vary somewhat, but the dimensions given in 
the table represent average practice. Column 3 gives the square 
feet of heating surface in a single row of pipes of the dimensions given 
in columns 1 and 2; and column 4 gives the free area between the 
pipes. 

TABLE XXXI 
Dimensions of Heaters 


Width of Section 

Height of Pipes 

Square Feet of 
Surface 

Free Area through 
Heater in Sq. Ft. 

3 feet 

3 feet 6 inches 

20 

4.2 

3 “ 

4 


0 

il 

22 

4.8 

3 “ 

4 

ii 

6 

ii 

25 

5.4 

3 “ 

5 

ii 

0 

it 

28 

6.0 

4 “ 

4 

a 

6 

(i 

34 

7.2 

4 “ 

5 

a 

0 

ii 

38 

8.0 

4 “ 

5 


6 

ii 

42 

8.8 

4 “ 

6 

ii 

0 

U 

45 

9.6 

5 “ 

5 

n 

6 

ii 

52 

11.0 

5 “ 

6 

a 

0 

ii 

57 

12.0 

5 “ 

6 

a 

6 

ii 

62 

13.0 

5 “ 

7 

a 

0 

ii 

67 

14.0 

6 “ 

6 

a 

6 

ii 

75 

15.6 

6 “ 

7 

it 

0 

it 

81 

16.8 

6 “ 

7 

a 

6 

“ 

87 

18.0 

6 “ 

8 


0 

ii 

92 

19.2 

7 “ 

7 

it 

6 

** 

98 

21.0 

7 “ 

8 

ii 

0 

ii 

108 

22.4 

7 “ 

8 

a 

6 


109 

23.8 

7 “ 

9 

• ii 

0 

it 

116 

25.2 


In calculating the total height of the heater, add 1 foot for the 
base. 

These sections are made up of 1-inch pipe, except the last or 
7-foot sections, which are made of lj-inch pipe. 

Using this table in connection with the example just given, we 
should look in the last column for a section having a free area of 12.5 
square feet; here we find that a 5 feet by 6 feet 6 inches section has a 
free opening of 13 square feet and a radiating surface of 62 square 


165 

















156 


flKATi NU AJND VENTILATION 


feet. The conditions call for 10 rows of pipes and 10 X 62 = 620 
square feet of radiating surface, which is slightly more than called for, 
but which would be near enough for all practical purposes. 

EXAMPLE FOR PRACTICE 

Compute the dimensions of a heater to warm 20,000 cubic feet 
of air per minute from 10 below zero to 70 degrees above, with 5 
pounds steam pressure. 

Ans. 1,164 sq. ft. of rad. surface 10 pipes deep. 

25 sq. ft. free area through heater. 

Use twenty 5 ft. by 6 ft. sections, two side by side, which gives 
24 square feet area and 1,140 square feet of surface. 

The general method of computing the size of heater for any given 
building is the same as in the case of indirect heating. First obtain 
the B. T. U. required for ventilation, and to that add the heat loss 
through walls, etc.; and divide the result by the efficiency of the 
heater under the given conditions. 

Example. An audience hall is to be provided with 400,000 cubic feet 
of air per hour. The heat loss through walls, etc., is 250,000 B.T.U. per 
hour in zero weather. What will be the size of heater, and how many rows 
of pipe deep must it be, with 20 pounds steam pressure? 

40 0, 00 0 X 70 = 509;()90 B T u for ventilation. 

55 

Therefore 250,000 + 509,090 = 759,090 B. T. U., total to be supplied. 

We must next find to what temperature the entering air must 
be raised in order to bring in the required amount of heat, so that the 
number of rows of pipe in the heater may be obtained and its corre¬ 
sponding efficiency determined. We have entering the room for pur¬ 
poses of ventilation, 400,000 cubic feet of air every hour, at a tempera¬ 
ture of 70 degrees; and the problem now becomes: To what tem¬ 
perature must this air be raised to carry in 250,000 B. T. U. additional 
for warming? 

We have learned that 1 B. T. U. will raise 55 cubic feet of air 
1 degree. Then 250,000 B. T. U. will raise 250,000 X 55 cubic 
feet of air 1 degree. 

250,000 X 55 
400,000 + 

The air in this case must be raised to 70 + 34 = 104 degrees, to provide 


166 





HEATING AND VENTILATION 


157 


for both ventilation and warming. Referring to Table XXX, we find 
that a heater 12 pipes deep will be required, and that the corre¬ 
sponding efficiency of the heater will be 1,650 B. T. U. Then 75 -- *- - P 

1,650 

= 460 square feet of surface required. 

Efficiency of Cast=Iron Heaters. Heaters made up of indirect 
pin radiators of the usual depth, have an efficiency of at least 1,500 
B. T. U., with steam at 10 pounds pressure, and are easily capable of 
warming air from zero to 80 degrees or over when computed on this 
basis. The free space between the sections bears such a relation to 
the heating surface that ample area is provided for the flow of air 
through the heater, without producing an excessive velocity. 

The heater shown in Fig. 139 may be counted on for an effi¬ 
ciency at least equal to that of a pipe heater; and in computing the 
depth, one row of sections may be taken as representing 4 rows of 

Pipe- 

Pipe Connections. In the heater shown in Fig. 135, all the 
sections take their supply from a common header, the supply pipe 
connecting with the top, and the return being taken from the lower 
division at the end, as shown. 

In Fig. 137 the base is divided into two parts, one for live steam, 
and the other for exhaust. The supply pipes connect with the upper 
compartments, and the drips are taken off as shown.. Separate traps 
should be provided for the two pressures. 

The connections in Fig. 136 are similar to those just described, 
except that the supply and return headers, or bases, are drained 
through separate pipes and traps, there being a slight difference in 
pressure between the two, which is likely to interfere with the proper 
drainage if brought into the same one. This heater is arranged to 
take exhaust steam, but has a connection for feeding in live steam 
through a reducing valve if desired, the whole heater being under one 
pressure. 

In heating and ventilating work where a close regulation of 
temperature is required, it is usual to divide the heater into several 
sections,depending upon its size, and to provide each with a valve in the 
supply and return. In making the divisions, special care should be 
taken to arrange for as many combinations as possible. For example, 
a heater 10 pipes deep may be made up of three sections—one of 


167 



158 


HEATING AND VENTILATION 


2 rows, and two of 4 rows each. By means of this division, 2, 4, 6, 8, 
or 10 rows of pipe can be used at one tim'', as the outside weather 
conditions may require. 

When possible, the return from each section should be provided 
with a water-seal two or three feet in depth. In the case of overhead 
heaters, the returns may be sealed by the water-line of the boiler or 
by the use of a special water-line trap; but vertical pipe heaters 
resting on foundations near the floor are usually provided with siphon 
loops extending into a pit. If this arrangement is not convenient, a 
separate trap should be placed on the return from each section. 
The main return, in addition to its connection with the boiler or 



Fig. 140. Heater Made Up of Interchangeable Sections. 

pump receiver, should have a connection with the sewer for blowing 
out when steam is first turned on. Sometimes each section is pro¬ 
vided with a connection of this kind. 

Large automatic air-valves should be connected with each 
section; and it is well to supplement these with a hand pet-cock, 
unless individual blow-off valves are provided as described above. 

If the fan is driven by a steam engine, provision should be made 
for using the exhaust in the heater; and part of the sections should 
be so valved that they may be supplied with either exhaust or live 
steam. 


168 




















HEATING AND VENTILATION 


159 


Fig. 140 shows an arrangement in which all of the sections are 
interchangeable. 

From 50 to 60 square feet of radiating surface should be provided 
in the exhaust portion of the heater for each engine horse-power, 
and should be divided into at least three sections, so that it can be 
proportioned to the requirements of different outside temperatures. 

Pipe Sizes. The sizes of the mains and branches may be com¬ 
puted from the tables already given in Part II, taking into account 
the higher efficiency of the heater and the short runs of piping. 

Table XXXII, based on experience, has been found to give 
satisfactory results when the apparatus is near the boilers. If the 
main supply pipe is of considerable length, its diameter should be 
checked by the method previously given. 


TABLE XXXII 
Pipe Sizes 


Square Feet of Surface 

Diameter of Steam Pipe 

Diameter of Return 

150 

2 inches 

14 inches 

300 

24 “ 

H “ 

500 

3 

2 

700 

34 “ 

2 

1,000 

4 

24 “ 

2,000 

5 

24 “ 

3,000 

6 

3 “ 


Heaters of the patterns shown in Figs. 135, 136, and 137 are 
usually tapped at the factory for high or low pressure as desired, 
and these sizes may be followed in making the pipe connections. 

The sizes marked on Fig. 136 may be used for all ordinary work 
where the pressure runs from 5 to 20 pounds; for pressures above 
that, the supply connections may be reduced one size. 

FANS 

There are two types of fans in common use, known as the cen¬ 
trifugal fan or blower , and the disc fan or propeller. The former 
consists of a number of straight or slightly curved blades extending 
radially from an axis, as shown in Fig. 141. When the fan is in 
motion, the air in contact with the blades is thrown outward by the 
action of centrifugal force, and delivered at the circumference or 


169 














160 


HEATING AND VENTILATION 


periphery of the wheel. A partial vacuum is thus produced at the 
center of the wheel, and air from the outside flows in to take the 
place of that which has been discharged. 

Fig. 142 illustrates the action of a centrifugal fan, the arrows 
showing the path of the air. 

This type of fan is usually 
enclosed in a steel-plate 
casing of such form as to 
provide for the free move¬ 
ment of the air as it es¬ 
capes from the periphery 
of the wheel. An opening 
in the circumference of the 
casing serves as an outlet 
into the distributing ducts 
which carry the air to the 
various rooms. Another 
type of centrifugal fan, 
known as the “Conoidal” 
fan, is shown in Fig. 143; 
and a type of “multivane” 
fan, direct-connected to a steam turbine, is shown in Fig. 144. 

The discharge opening can be located in any position desired, 
either up, down, top horizontal, bottom horizontal, or at any angle. 

Where the height of the fan room is 
limited, a form called the three-quarter 
housing may be used, in which the lower 
part of the casing is replaced by a brick 
or cemented pit extending below the floor- 
level as shown in Fig. 145. 

Another form of centrifugal fan is 
shown in Fig. 146. This is known as the 
cone fan, and is commonly placed in an 
opening in a brick wall, and discharges air 
from its entire periphery into a room called 
a 'plenum chamber , with which the various 
distributing ducts connect. 

This fan is often made double by placing two wheels back to 



Fig. 142. Illustrating Action 
of Centrifugal Fan. The 
Arrows Show the Path of 
the Air. 



Fig. 141. Centrifugal Fan or Blower. 


170 











HEATING AND VENTILATION 


161 


back and surrounding them with a steel casing. In the conoidal 
fan which is shown in Fig. 143, the casing has been removed. 

Cone fans are particularly adapted to church and schoolhouse 
work, as they are capable of moving large volumes of air at moderate 
speeds, thus providing adequate ventilation without causing an 
influx of cold air. 


Fig. 14/ shows a form of small direct-connected exhauster com¬ 
monly used for ventilating toilet-rooms, chemical hoods, etc. This 
exhauster is driven by an electric motor and is of the up-discharge 
type. 



Centrifugal fans are used almost exclusively for supplying air 
for the ventilation of buildings, and for forced-blast heating. They 
are also used as exhausters for 
removing the air from buildings in 
cases where there is considerable 
resistance due to the small size or 
excessive length of the discharge 
ducts. 

General Proportions. The gen¬ 
eral form of a fan w T heel is shown 
in Fig. 141, which represents a 
single spider wheel with curved 
blades. Those over 4 feet in diam¬ 
eter usually have tv T o spiders, while 
fans of large size are often provided 
with three or more. The number 
of floats or blades commonly varies 
from six to twelve, depending upon 
the diameter of the fan. They 
are made both curved and straight; the former, it is claimed, run 
more quietly, but, if curved too much, will not work so well against 
a high pressure as the latter form. 

The relative proportions of a fan wheel vary somewhat in the 
case of different makes. The following are averages taken from fans 
of different sizes as made by several well-known manufacturers for 
general ventilating and similar work: 


Fig. 143. Conoidal Fan without Casing. 
Courtesy of Buffalo For ye Company, 
Buffalo, New York. 


Width of fan at center = Diameter X .52 
Width of fan at perimeter = Width at center X .8 
Diameter of inlet = Diameter of wheel X .68 


171 


162 


HEATING AND VENTILATION 



Fig. 144. “Multivane” Fan with Direct-Connected Turbine. 
Courtesy of B. F. Sturtevant Company, Hyde Park, Massachusetts. 



Fig. 145. Steel Plate Steam Fan with Three-Quarter Housing and Single. 
Upright Engine 

Courtesy of B. F. Sturtevant Company, Hyde Park, Massachusetts. 


172 


















HEATING AND VENTILATION 


163 


Fans are made both with double and with single inlets, the 
former being called blowers and the latter exhausters. The size of 
a fan is commonly expressed in inches, which means the approximate 
height of the casing of a full-housed fan. The diameter of the wheel 
is usually expressed in feet, and can be found in any given case by 
dividing the size in inches by 20. For example, a 120-inch fan has a 
wheel 120 20 = 6 feet in diameter. 



Fig. 146. “Cone” Fan. Discharges throiigh Opening in Wall into a “Plenum Chamber’* 
Connecting with Distributing Ducts. 


Theory of Centrifugal Fans. The action of a fan is affected 
to such an extent by the various conditions under which it operates, 
that it is impossible to give fixed rules for determining the exact 
results to be expected in any particular instance. This being the 
case, it seems best to take up the matter briefly from a theoretical 


173 



164 


HEATING AND VENTILATION 



standpoint, and then show what corrections are necessary in the 
case of a given fan under actual working conditions. 

There are various methods for determining the capacity of. a 
fan at different speeds, and the power necessary to drive it; each 
manufacturer has his own formulae for this purpose, based upon 
tests of his own particular fans. The methods given here apply 
in a general way to fans having proportions which represent the 
average of several standard makes; and the results obtained will be 


Fig. 147. Motor-Driven Exhauster for Ventilating Toilet-Rooms, Chemical Hoods, etc. 

Courtesy of Buffalo Forge Company, Buffalo, New York. 

found to correspond well with those obtained in practice under 
ordinary conditions. 

As already stated, the rotation of a fan of this type sets in motion 
the air between the blades, which, by the action of centrifugal force, 
is delivered at the periphery of the wheel into the casing surrounding 
it. As the velocity of flow through the discharge outlet depends 
upon the pressure or head within the casing, and this in turn upon 
the velocity of the blades, it becomes necessary to examine briefly 
into the relations existing between these quantities. 


174 






HEATING AND VENTILATION 


165 


Pressure. The pressure referred to in connection with a fan, 
is that in the discharge outlet, and represents the force which drives 
the air through the ducts and flues. The greater the pressure with a 
given resistance in the pipes, the greater will be the volume of air 
delivered; and the greater the resistance, the greater the pressure 
required to deliver a given quantity. 

The pressure within a fan casing is caused by the air being 
thrown from the tips of the blades, and varies with the velocity of 
rotation; that is, the higher the speed of the fan, the greater will be 
the pressure produced. Where the dimensions of a fan and casing 
are properly proportioned, the velocity of air-flow through the outlet 
will be the same as that of the tips of the blades, and the pressure 
within the casing will be that corresponding to this velocity. 

Table XXXIII gives the necessary speed for fans of different 
diameters to produce different pressures, and also the velocity of air¬ 
flow due to these pressures. 

TABLE XXXIII 

Fan Speeds, Pressures, and Velocities of Air=FIow 


Pressure, in 
Ounces per 

Sq. Inch 

Diameter of Fan Wheel, in Feet 

Velocity of 
Flow, in Feet 
per Minute 

3 

4 

5 

6 

7 

8 

9 

10 

Revolutions per Minute 

i 

274 

206 

164 

137 

117 

103 

92 

82 

2,585 

1 

336 

252 

202 

168 

144 

126 

112 

101 

3,165 


338 

291 

232 

194 

166 

146 

129 

116 

3,653 

f 

433 

325 

260 

217 

186 

163 

144 

130 

4,084 


The application of this table will be made plain by a brief dis¬ 
cussion of blast area. 

Blast Area. When the outlet from a fan casing is small, the air 
will pass out with a velocity equal to that of the tips of the blades; and 
the pressure within the casing will be that corresponding to the 
tip velocity. That is, a 3-foot fan wheel revolving at a speed of 274 
revolutions per minute will produce a pressure within the fan casing 
of \ ounce per square inch, and will cause a velocity of flow through 
the discharge outlet of 2,585 feet per minute (see Table XXXIII). 


175 

























166 


HEATING AND VENTILATION 


Now, if the opening be slowly increased, while the speed of the fan 
remains constant, the air will continue to flow with the same velocity 
until a certain area of outlet is reached. If the outlet be still further 
increased, the pressure in the casing will begin to drop, and the 
velocity of outflow become less than the tip velocity. The effective 
area of outlet at the point when this change begins to take place, is 
called the blast area or capacity area of the fan. This varies some¬ 
what with different types and makes of fans; but for the common 
form of blower, it is approximately J of the projected area of the fan 

opening at the periphery—that is, —> in which D is the diameter 


of the fan wheel, and w its width at the periphery. It has already 
been stated under “General Proportions” that W = .52 D, and w = .8 


W ; so that we may write A 


D X .8 (V 
3 


DX.8X .52 D 
3 


= .14 D 2 y 


in which A = the blast area, and D the diameter of the fan. 

As a matter of fact, the outlet of a fan casing is always made 
larger than the blast area; and the result is that the pressure drops 
below that due to the tip velocity, and the velocity of flow through 
the outlet becomes less than that given in the last column of Table 
XXXIII for any given speed of fan. 

Effective Area of Outlet. The size of discharge outlet varies 
somewhat for different makes; but for a large number of fans ex¬ 
amined it was found to average about 2.22 times the blast area 
as computed by the above method. When air or a liquid flows 
through an orifice, the stream is more or less contracted, depending 
upon the form of the orifice. 

In the case of a fan outlet, the effective area may be taken as about 
.8 of the actual area. This makes the effective area of a fan outlet 
equal to .8 X 2.22 = 1.78 times the blast area. 

Table XXXIV gives the effective areas of fans of different 
diameter as computed by the above method. That is, Effective 
area = .14D 1 X 1.78 = .25 D\ 

Speed. We have seen that when the discharge outlet is made 
larger than the blast area, the pressure within the fan casing drops 
below that due to the tip velocity; so that, in order to bring the pres¬ 
sure up to its original point, the speed of the fan must be increased 
above that given in Table XXXIII. 





HEATING AND VENTILATION 


167 


TABLE XXXIV 
Effective Areas of Fans 


Diameter of Fan, in Feet 

Effective Area of Outlet, in 
Square Feet 

3 

2.3 

4 

4.0 

5 

6.3 

6 

9.1 

7 

12.3 

8 

16.0 

9 

20.4 

10 

25.2 


Tests upon a fan of practically the same proportions as those 
previously given, show that, when the effective outlet area is made 
1.78 the blast area, the speed must be increased 1.2 times in order 
to keep the pressure at the same point as when the outlet is equal 
to or less than the blast area. 

Capacity. The capacity of a fan is the volume of air discharged 
in a given time, and is usually expressed in cubic feet per minute. 
It is equal to the effective area of discharge multiplied by the velocity 

of flow through it. 

Example. At what speed must a 6-foot fan be run to maintain a pres¬ 
sure of | ounce, and what volume of air will be delivered per minute? 

From Table XXXIII we find that a 6-foot fan must run at a 
speed of 194 revolutions per minute to maintain the given pressure 
when the outlet is equal to the blast area, or 194 X 1 -2 = 233 revo¬ 
lutions per minute under actual conditions. The velocity of flow 
through the outlet at \ ounce pressure, is 3,653 feet per minute (Table 
XXXIII); and the effective area of outlet of a 6-foot fan is 9.1 square 
feet (Table XXXIV). Therefore the volume of air delivered per 
minute is equal to 9.1 X 3,653 = 33,242 cubic feet. 

Example. It is desired to move 52,000 cubic feet of air per 
minute at a pressure of } ounce. What size and speed of fan will 
be required? Looking in Table XXXIII, we find that the velocity 
through the fan outlet for J-ounce pressure is 2,585, which calls for 
an outlet area of 52,000 -r 2,585 = 20.1 square feet. Looking in 
Table XXXIV, we find this corresponds very nearly to a 9-foot fan, 
which is the size called for. Referring again to 4 able XXXIII, the 
speed necessary to maintain the required pressure under the given 
conditions is found to be 92 X 1 .2 - 110 revolutions per minute. 


177 









168 


HEATING AND VENTILATION 


Effect of Resistance. Thus far it has been assumed that the 
fan was discharging into the open air against atmospheric pressure. 
The effect of adding a resistance by connecting it with a series of 
ventilating ducts, is the same as partially closing the discharge outlet. 
Carefully conducted tests upon this type of fan have shown that the 
reduction of air-flow is very nearly in proportion to the reduction 
of the discharge area. That is, if the outlet of the fan is closed to 
one-half its original area, the quantity of air discharged will be prac¬ 
tically one-half that delivered by the fan with a free opening. The 
effect of attaching a fan to the ventilating flues of a building like a 
schoolhouse, church, or hall, where the ducts have easy bends and 
where the velocity of air-flow through them is not over 1,000 to 1,200 
teet per minute, is about the same as reducing the outlet 20 per cent. 
For factories with deep heaters and smaller ducts, where the velocity 
runs up to 1,500 or 1,800 feet per minute, the effect is equivalent to 
closing the outlet at least 30 per cent, and even more in very large 
buildings. 

For schoolhouses and similar work a fan should not be run much 
above the speed necessary to maintain a pressure of | ounce at the 
outlet. Higher speeds are accompanied with greater expenditure of 
power, and are likely to produce a roaring noise or to cause vibration. 

A much lower speed does not provide sufficient pressure to give proper 
control of the air-distribution during strong winds. For factories, 
a higher pressure of f to f ounce is more generally employed. 

Actually the pressure is increased slightly by restricting the out¬ 
let at constant speed; but this is seldom taken into account in venti¬ 
lating work, as volume, speed, and power are the quantities sought. 

Example. A school building requires 32,000 cubic feet of air per min¬ 
ute. What size and speed of fan will be required? « 

If the resistance of the ducts and flues is equivalent to cutting 
down the discharge outlet 20 per cent, we must make the computa¬ 
tions for a fan which will discharge 32,000 - 5 - .8 = 40,000 cubic feet 
in free air. 

Looking in Table XXXIII, we find the velocity for f-ounce 
pressure to be 3,165 feet per minute; therefore the size of fan outlet 
must be 40,000 3,165 — 12.6 square feet, which, from Table 

XXXIV, we find corresponds very nearly to a 7-foot fan. 




HEATING AND VENTILATION 


160 


Referring again to Table XXXIII, the required speed is found 
to be 144 X 1.2 = 173 revolutions per minute. 

Example. A factory requires 21,000 cubic feet of air per minute for 
warming and ventilating. What size and speed of fan will be required? 

21,000 -f* .7 = 30,000, the volume to provide for with a fan 
discharging into free air. Assuming a pressure of f ounce, the veloc¬ 
ity will be 4,084 feet per minute, from which the area of outlet is 
found to be 30,000 -r- 4,084 = 7.3 square feet. This, we find, does 
not correspond to any of the sizes given in Table XXXIV. As 
standard fans are not usually made in half-sizes above 5 feet, we 
shall use a 5-foot fan and run it at a higher speed. 

A 5-foot fan has an outlet area of 6.3 square feet, and at f-ounce 
pressure it would deliver 6.3 X 4,084 = 25,729 cubic feet of air per 
minute, at a speed of 260 X 1.2 = 312 revolutions per minute. 
The volume of air delivered by a fan varies approximately as the 
speed; so, in order to bring the volume up to the required 30,000, the 
speed must be increased by the ratio 30,000 -5- 25,729 = 1.16, 
making the final speed 312 X 1.16 = 362 revolutions per minute. 
In the same way, a 6-foot fan could have been used and run at a 
proportionally lower speed. 

Power Required. The work done by a fan in moving air is 
represented by the pressure exerted, multiplied by the distance through 
which it acts. 

Table XXXV gives the horse-power required for moving the 
air which will flow through each square foot of the effective outlet 
area, under different pressures. 

This table gives only the power necessary for moving the air, 
.and does not take into consideration the friction of the air in passing 
through the fan, nor that of the fan itself. 

The efficiency of a fan varies with the speed, the size of outlet, 
and the pressure against which the fan is working. Under favorable 
conditions, with properly proportioned fans, we may count on an 
efficiency of about .35. 

Example. What horse-power will be required to drive an 8-foot fan at 
such a speed as to maintain a pressure of £ ounce? 

An 8-foot fan has an outlet area of 16 square feet (Table XXXIV); 
and from Table XXXV we find that .5 horse-power is required to 
move the air which will flow through each square foot of outlet under 


179 


170 


HEATING AND VENTILATION 


TABLE XXXV 


Power Required for Moving Air under Different Pressures 


Pressure in 


Ounces per Square Inch 


Horse-Power for Moving Air which will 
Flow through Each Square Foot of 
Effective Outlet Area 


i 

I 

h 

I 


.18 

.33 

.50 

.70 


^-ounce pressure. Therefore the power required to move the air 
alone is 16 X .5 = 8, and the total horse-power is 8 -f- .35 = 23. 

Effect of Resistance . In the above case, it is assumed that the 
fan is discharging into free air. If a resistance is added, the effect 
is the same as partially closing the outlet, and the volume of air 
moved and the horse-power required are both reduced in very nearly 
the same proportion. This reduction, as already stated, may be 
taken as 20 per cent for schoolhouse and similar work, and 30 per 
cent for factories. 

For example, if the fan just considered was to be used for venti¬ 
lating a schoolhouse, delivering air under a pressure of \ ounce, the 
necessary horse-power would be only 23 X .8 = 18.4. If used for 
a factory, delivering air under a pressure of | ounce, the required 


horse-power would be 


16 X 
.35 


X .7 = 22.3. 


General Rules. The methods above described may be briefly 


expressed as follows: 

Capacity— Q = A X v X F, in which 
Q = Cubic feet of air per minute; • 

A = Effective area of fan outlet (Table XXXIV); 
v = Velocity of flow through outlet; 

3,165 (§-ounce pressure) for schoolhouses, etc.; 

4,084 (f-ounce pressure) for factories; 
p, j .8 for tchoolhouses, etc.; 

"j .7 for factories. 

Speed —Take the speed from Table XXXIII, corresponding to the giver 

pressure and size of fan, and multiply by 1 ? 

A X v X F . ... 

- - -, in which 

.o5 


Horse-Power —H.P. 


H.P. = Horse-power; 

A = Effective area of fan outlet; 

p = Horse-power to move air which will flow through 1 square foot of far 
outlet under given pressure (Table XXXV); 


180 



















HEATING AND VENTILATION 


171 


j .33 for schoolhouses, etc.; 
| .7 for factories, 
j .8 for schoolhouses, etc.; 

1 -7 for factories. 


EXAMPLES 

1. A schoolhouse requires an air-supply of 30,000 cubic feet 

per minute. What will be the required size of fan, its speed, and 
the H. P. of engine to drive it? f 7 ft. in diameter. 

Ans. \ 173 r. p. m. 

[9 H.P. 

2. What will be the size and speed of fan, and horse-power of 

engine, to heat and ventilate a factory requiring 1,080,000 cubic feet 
of air per hour? f 5 ft. in diameter. 

Ans. 312 r. p. m. 

L8.8H.P. 

General Relations. The following general relations between the 
volume, pressure, and power will often be found useful in deciding 
upon the size of a fan: 

(1) The volume of air delivered varies directly as the speed of the fan; 
that is, doubling the number of revolutions doubles the volume of air de¬ 
livered. 

(2) The pressure varies as the square of the speed. For example, if 
the speed is doubled, the pressure is increased 2X2 = 4 times; etc. 

(3) The power required to run the fan varies as the cube of the speed. 
Thus, if thq speed is doubled, the power required is increaied 2 X 2 X 2 = 8 
times; etc. 

The value of a knowledge of these relations may be illustrated 
by the following example: 

Suppose for any reason it were desired to double the volume of 
air delivered by a certain fan. At first thought we might decide to 
use the same fan and run it twice as fast; but when we come to con¬ 
sider the power required, we should find that this would have to be 
increased 8 times, and it would probably be much cheaper in the 
long run to put in a larger fan and run it at lower speed. 

Disc or Propeller Fans. When air is to be moved against a very 
slight resistance, as in the case of exhaust ventilation, the disc or pro¬ 
peller type of wheel may be used. This is shown in different forms 
in Figs. 149 and 150. This type of fan is light in construction, re¬ 
quires but little power at low speeds, and is easily erected. It may be 


181 


172 


HEATING AND VENTILATION 


conveniently placed in the attic or upper story of a building, where 
it may be driven either by a direct- or belt-connected electric motor. 
Fig. 148 shows a fan equipped with a direct-connected motor, and 
Fig. 151 the general arrangement when a telted motor is used. These 
fans are largely used for the ventilation of toilet aiid smoking rooms, 
restaurants, etc., and are usually mounted in a wall opening, as shown 
in Fig. 151. A damper should always be provided for shutting off 
the opening when the fan is not in use. The fans shown in Figs. 149 
and 150 are provided with pulleys for belt connection. 



Fig. 148. Propeller Fan Direct-Connected to Motor. 


Fans of this kind are often connected with the main verlt flues 
of large buildings, such as schools, halls, churches, theaters, etc., 
and are especially adapted for use in connection with gravity heating 
systems. They are usually run by electric motors, and as a rule are 
placed in positions where an engine could not be connected, and also 
in buildings where steam pressure is not available. 

Capacity of Disc Fans. The capacity of a disc fan varies greatlv 
with the type and the conditions under which it operates. The rated 


182 





HEATING AND VENTILATION 


173 


capacities usually given in catalogues are for fans revolving in free 
air that is, mounted in an opening without being connected with 
ducts or subjected to other frictional resistance. 

As the capacity and necessary power are so dependent upon the 
resistance to be overcome, it is difficult to give definite rules for 
determining them. The following data, based upon actual tests, 



apply to fans working against a resistance such as would be 
produced by connecting with a system of ducts of medium length 
through which the air was drawn at a velocity not greater than 600 
or 800 feet per minute. Under these conditions, a good type of fan 
will propel the air in a direction parallel to the shaft a distance equal to 
about .7 of its diameter at each revolution; and from this we have 
the equation: 


183 




174 HEATING AND VENTILATION 

Q = .7 DXRXA, 

in which 

Q = Cubic feet of air discharged per minute; 

D = Diameter of fan, in feet; 

R = Revolutions per minute; 

A = Area of fan, in square feet. 

In order to obtain the 
best results, the linear velocity 
of air-flow through th& fan 
should range from 800 to 1,200 
feet per minute. 

Table XXXVI gives the 
revolutions per minute for 
fans of different diameter to 
produce a linear velocity of 
1,000 feet, the volume deliv¬ 
ered at this speed, and the 
horse-power required. 

The horse-power is com¬ 
puted by allowing .14 H. P. 
for each 1,000 cubic feet of 
air moved, when the velocity 
through the fan is 800 feet 
per minute; .16 H. P. for 


1,000 feet velocity; and .18 H. P. for 1,200 feet velocity. These 
factors are empirical, and based on tests. 



Example. Assuming a velocity of 800 feet per minute through a 4-foot 
fan, what volume will be delivered per minute, and what speed and horse¬ 
power will be required ? 



Fig. 150. Propeller Fan with Wheel on Shaft 
for Belt Connection. 


184 

















































HEATING AND VENTILATION 




5 


TABLE XXXVI 

Disc Fans, their Capacity, Speed, etc. 


Dia. of Fan, in 
Inches 

Rev. per Min. 

Cubic Feet of Air 
Moved 

Horse-Power 

Required 

18 

952 

1,700 

.27 

24 

716 

3,100 

.50 

30 

572 

4,900 

.78 

36 

476 

7,100 

1.2 

42 

408 

9,400 

1.5 

48 

343 

12,000 

1.9 

54 

317 

* 15,800 

2.5 

60 

286 

19,400 

3.1 

72 

238 

28,300 

4.5 


The area of a 4-foot fan is 12.5 square feet; and at 800 velocity 
the volume would be 12.5 X 800 = 10,000 cubic feet. Next solve 
for the speed by the equation Q = .7 D X R X A, which, when 
transposed, takes the form 

p_ Q . 

" ” .7 D X A 


Substituting the known quantities, we have 

10,000 


R = 


= 286 


' .7 X 4 X 12.5" 

The horse-power is 10X .14 = 1.4. 

Fan Engines. A simple, quiet-running engine is desirable 
for use in connection with a fan or blower. The engine may be either 
horizontal or vertical; and for schoolhouse and similar work, should 
be provided with a large cylinder, so that the required power may 
be developed without carrying a boiler pressure much above 30 
pounds. In some cases, cylinders of such size are used that a boiler 
pressure of 12 or 15 pounds is sufficient. The quantity of steam 
which an engine consumes is of minor importance, as the exhaust can 
be turned into the coils and used for heating purposes. If space 
allows, the engine should always be belted to the fan. Where it is 
direct-connected, as in Fig. 144, there is likely to be trouble from 
noise, as any slight looseness or pounding in the engine will be com¬ 
municated to the air-ducts, and the sound will be carried to the rooms 


185 
































176 HEATING AND VENTILATION 

above. Figs. 152 and 153 show common forms of fan engines. The 
latter is especially adapted to this purpose, as all bearings are enclosed 


Fig. 152. Vertical Self-Oiling Fan Engine'. 

Courtesy of the American Blower Company, Detroit, Michigan. 

and protected from dust and grit. A horizontal engine for fan use 
is shown in Fig. 154. 

In case an engine is belted, the distance between the shafts of 
the fan and engine should not in general be much less than 10 feet 


186 







HEATING AND VENTILATION 


177 


for fans up to 7 or 8 feet in diameter, and 12 feet for those of larger 
size. When possible, the tight or driving side of the belt should 
be at the bottom, so that the loose side, coming on top, will tend to 
wrap around the pulleys and so increase the arc of contact. 

Motors. Electric motors are especially adapted for use in 
connection with fans. This method of driving is more expensive 



Fig. 153. Another Form of Fan Engine, with Bearings Enclosed to Protect Them 
from Dust and Grit. 


than by the use of an engine, especially if electricity must be pur¬ 
chased from outside parties; but if the building contains its own 
power plant, so that the exhaust steam can be utilized for heating, 
the convenience and simplicity of motor-driven fans often more than 
offset the additional cost of operation. 


187 






178 


HEATING AND VENTILATION 


Direct-connected motors are always preferable to belted, if a 
direct current is available, on account of greater quietness of action. 
This is due both to the slower speed of the motor and to the absence 
of belts. 

Sufficient speed regulation can be obtained with direct-connected 
machines, without excessive waste of energy, by putting a rheostat 
in the motor circuit. 

If a direct current is not available and an alternating current 
must be used, the advantages of electric driving are somewhat 
reduced, as high-speed motors with belts or other reducing gear must 
be employed, and, furthermore, satisfactory speed regulation is not 
easily attainable. 



Fig. 154. Horizontal Engine for Fan Use. 
Courtesy of Buffalo Forge Company, Buffalo, New York. 


Area of Ducts and Flues. With the blower type of fan, the size 
of the main ducts may be based on a velocity of 1,200 to 1,500 feet per 
minute; the branches, on a velocity of 1,000 to 1,200 feet per minute, 
and as low as 600 to 800 feet when the pipes are small. Flue veloci¬ 
ties of 500 to 700 feet per minute may be used, although the lower 
velocity is preferable. The size of the inlet register should be such 
that the velocity of the entering air will not exceed about 300 feet per 
minute; while, on the other hand, the velocity between the inlet 
windows and the fan or heater should not exceed about 800 feet per 
minute. 

The air-ducts and fl.ues are usually made of galvanized iron, the 


188 




HEATING AND VENTILATION 


179 


ducts being run at the basement ceiling. No. 20 and No. 22 iron 
is used for the larger sizes, and No. 24 to No. 28 for the smaller. 

Regulating dampers should 
be placed in the branches lead¬ 
ing to each flue, for increasing or 
reducing the air-supply to the 
different rooms. Adjustable de¬ 
flectors are often placed at the 
fork of a pipe for the same pur¬ 
pose. One o f these is shown in 
Fig. 155. 

Fig. 156 illustrates a com¬ 
mon arrangement of fan and 
heater where the type of heater 
shown in Fig. 138 is used; and 
Fig. 157 is a self-contained apparatus in which the heater is inclosed 
in a steel casing. 

Factory Heating. The application 



Fig. 155. Adjustable Deflector Placed at Fork 
of Pipe to Regulate Air-Supply. 


COLD A/P /MLET W/NDOWS 


of forced blast for the 
warming of factories and 
shops, is shown in Figs. 
158 and 159. The pro¬ 
portional heating surface 
in this case is generally 
expressed in the number 
of cubic feet in the 
building for each linear 
foot of 1-inch steam 
pipe in the heater. On 
this basis, in factory 
practice, with all of the 
air taken from out of 
doors, there are generally 
allowed from 100 to 150 
cubic feet of space per 
foot of pipe, according as 
exhaust or live steam 
is used, live steam in this case indicating steam of about 80 
pounds pressure. If practically all the air is returned from the 



1 D/SCHAPGC 
DUCr ff>OM 
BLOWCP Arce/L/PG 


Fig. 156. Common Arrangement of Fan with Heater 
of Type Shown in Fig. 138. 















































180 HEATING AND VENTILATION 

buildings to the heater, these figures may be raised to about 140 as a 
minimum, and possibly 200 as a maximum, per foot of pipe. The 



heaters in Table XXXI may be changed to linear feet of 1 inch pipe 
by multiplying the numbers in column three (sauare feet of surface) 
by three. 


190 






HEATING AND VENTILATION 


181 


EXAMPLES FOR PRACTICE 


1* ^ mac hine shop 100 feet long by 50 feet wide and having 3 
stories, each 10 feet high, is to be warmed by forced blast, using 



Fig. 158. Illustrating Application of Forced Blast for Warming a Factory. 


exhaust steam in the heater. The air is to be returned to the heater 
from the building, and the whole amount contained in the building 
is to pass through the heater every 15 minutes. What size of blower 


191 




























































































182 


HEATING AND VENTILATION 


will be required, and what will be the H. P. of the engine required to 
run it? How many linear feet of 1-inch pipe should the heater con¬ 
tain? 


Ans. < 


4-foot blower. 

6 H. P. engine. 
1,071 feet of pipe. 



Fig. 159. Centrifugal Blower Producing Forced Blast for Heating a Shop. 

2. Find the size of blower, engine, and heater for a factory 
200 feet long, 60 feet wdde, and having 4 stories, each 10 feet high, 
using live steam at 80 pounds pressure in the heater, and changing 
the air every 20 minutes by taking in cold air from out of doors. 

6-foot blower. 

* 13 H. P. engine. 
3,200 feet of pipe. 


Ans. 




















































HEATING AND VENTILATION 


183 


In using this method of computation, judgment must be employed, 
which can come only from experience. The figures given are for 
average conditions of construction and exposure. 

Double=Duct System. The varying exposures of the rooms of 
a school or other building similarly occupied, require that more heat 
shall be supplied to some than to others. Rooms that are on the 
south side of the building and exposed to the sun, may perhaps be 
kept perfectly comfortable with a supply of heat that will maintain 
a temperature of only 50 or 60 degrees in rooms on the opposite side 
of the building which are exposed to high winds and shut off from the 
warmth of the sun. 



Fig. 160. Hot-Blast Apparatus with Double Duct for Supplying Air at Different Temper¬ 
atures to Different Parts of a Building. 


With a constant and equal air-supply to each room, it is evident 
that the temperature must be directly proportional to the cooling 
surfaces and exposure, and that no building of this character can be 
properly heated and ventilated if the temperature cannot be varied 
without affecting the air-supply. 

There are two methods of overcoming this difficulty: 

The older arrangement consists in heating the air by means of a 
primary coil at or near the fan, to about 60 degrees, or to the minimum 
temperature required within the building. From the coil it passes 
to the bases of the various flues, and is there still further heated as 
required, by secondary or supplementary heaters placed at the base of 
each flue. 


193 








184 


HEATING AND VENTILATION 


With the second and more recent method, a single heater is 
employed, and all the air is heated to the maximum required to 
maintain the desired temperature in the most exposed rooms, while 
the temperature of the other rooms is regulated by mixing with the 
hot air a sufficient volume of cold air at the bases of the different flues. 
This result is best accomplished by designing a hot-blast apparatus 

so that the air shall be 
forced, rather than drawn 
through the heater, and 
by providing a by-pass 
through which it may 
be discharged without 
passing across the heated 
pipes. 

The passage for the 
cool air is usually above 
and separate from the 
heater pipes, as shown in 
Fig. 160. Extending 
from the apparatus is a 
double system of ducts, 
usually of galvanized 
iron, suspended from the 
ceiling. At the base of 
each flue is placed a mix¬ 
ing damper, which is 
controlled by a chain 
from the room above, 
and so * designed as to 
admit either a full vol¬ 
ume of hot air, a full 
volume of cool 
tempered air, or to mix them in any desired proportion without 
affecting the resulting total volume delivered to the room, Fig. 166. 

Fig. 162 shows an arrangement of disc fan and heater where the 
air is first drawn through a tempering coil, then a portion of it forced 
through a second heater and into the warm-air pipes, while the 
remainder is by-passed under the heater into the cold-air pipes. 



Fig. 161. Mixing Damper for Regulating Temperat ure 
of Air Supplied by Double-Duct System. 


194 












































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195 


































































































































































































































































.186 


HEATING AND VENTILATION 


ELECTRIC HEATING 

Unless electricity is produced at a very low cost, it is not com¬ 
mercially practicable for heating residences or large buildings. The 
electric heater, however, has quite a wide field of application in heating 
small offices, bathrooms, electric cars, etc. It is a convenient method 
of warming rooms on cold mornings in late spring and early fall, 
when furnace or steam heat is not at hand. It has the special advan¬ 
tage of being instantly available, and the amount of heat can be regu¬ 
lated at will. The heaters are perfectly clean, do not vitiate the air, 
and are portable. 

Electric Heat and Energy. The commercial unit for electricity 
is one watt for one hour, and is equal to 3.41 B. T. U. Electricity is 
usually sold on the basis of 1,000 watt-hours (called Kilowatt-hours ), 



Fig. 163. Electric Car-Heater. 


which is equivalent to 3,410 B. T. U. A watt is the product obtained 
by multiplying a current of .1 ampere by an electromotive force of 1 
volt. 

From the above we see that the B. T. U. required per hour for 
warming, divided by 3,410, will give the kilowatt-hours necessarv for 
supplying the required amount of heat. 

Construction of Electric Heaters. Heat is obtained from the 
electric current by placing a greater or less resistance in its path. 
Various forms of heaters have been employed. Some of the simplest 
consist merely of coils or loops of iron wire, arranged in parallel rows, 
so that the current can be passed through as many coils as are needed 
to provide the required amount of heat. In other forms, the heating 
material is surrounded with fire-clay, enamel, or asbestos, and in some 
cases the material itself has been such as to give considerable resist¬ 
ance to the current'. A form of electric car-heater is shown in Fig. 163, 
Forms of radiators are shown in Figs. 164 and 165. 


196 


HEATING AND VENTILATION 


187 


Calculation of Electric Heaters. The formula for the calcu¬ 
lation of electric heaters is 


H -P R tx .24, 

in which 

H = Heat, in calories; 

I — Current, in amperes; 

R — Resistance, in ohms; 
t = Time, in seconds. 

Examples. What resistance must an 
electric heater have, to give off 6,000 B. 
T. U. per hour, with a current of 20 am¬ 
peres ? 



Fig. 164. Electric Radiator. 


We have learned that 1 B. T. U. = 252 calories; so, in the 
present case, 6,000 X 252 = 1,512,000 calories must be provided. 
Substituting the known values in the formula, we have 


from which , 


1,512,000 = 20 2 X R X 3,600 X .24, 


R — 


1,512,000 

345,600 


= 4.37 ohms. 


A heater having a resistance of 3 ohms is to supply 3,000 B. T. U. per 
hour. What current will be required ? 



Fig. 165. Another Form of Electric Radiator. 


3,000 X 252 = 756,000 calories. Substituting the known values in 
the formula, and solving for I, we have 

756,000 = 7 2 X 3 X 3,600 X .24, 


from which 


I = V 291.6 = 17 + amperes. 


Connections for Electric Heaters. The method of wiring for 
electric heaters is essentially the same as for lights which require the 
same amount of current. A constant electromotive force or voltage 


197 











188 


HEATING AND VENTILATION 


is maintained in the main wire leading to the heaters. A much less 
voltage is carried on the return wire, and the current in passing through 
the heater from the main to the return, drops in voltage or pressure. 
This drop provides the energy which is transformed into heat. 

The principle of electric heating is much the same as that in¬ 
volved in the non-gravity return system of steam heating. In that 
system, the pressure on the main steam pipes is that of the boiler, 
while that on the return is much less, the reduction in pressure occur¬ 
ring in the passage of the steam through the radiators; the water of 
condensation is received into a tank, and returned to the boiler by a 
pump. 

In a system of electric heating, the main wires must be- suffi¬ 
ciently large to prevent a sensible reduction in voltage or pressure 
between the generator and the heater, so that the pressure in them 
shall be substantially that in the generator. The pressure or voltage 
in the main return wire is also constant, but very low, and the genera¬ 
tor has an office similar to that of the steam pump in the system just 
described—that is, of raising the pressure of the return current up 
to that in the main. The power supplied to the generator can be 
considered the same as the boiler in the first case. All the current 
which passes from the main to the return must flow through the heater, 
and in so doing its pressure or voltage falls from that of the main 
to that of the return. 

From the generator shown in Fig. 166,- main and return wires 
are run the same as in a two-pipe system of steam heating, and these 
are proportioned to carry the required current without sensible drop 
or loss of pressure. Between these wires are placed the various 
heaters, which are arranged so that when electric connection is made 
they draw the current from the main and discharge it into the return 
wire. Connections are made and broken by switches, which take the 
place of valves on steam radiators. 

Cost of Electric Heating. The expense of electric heating must 
in every case be great, unless the electricity can be supplied at an 
exceedingly low cost. Estimated on the basis of present practice, 
the average transformation into electricity does not account for more 
than 4 per cent of the energy in the fuel which is burned in the furnace. 
Although under best conditions 15 per cent has been realized, it 
would not be safe to assume that in ordinary practice more than 5 


198 


HEATING AND VENTILATION 


189 


per cent could be transformed into electrical energy. In heating 
with steam, hot water, or hot air, the average amount utilized will 
probably be about 60 per cent, so that the expense of electrical heating 
is approximately from 12 to 15 times greater than by these methods. 

TEMPERATURE REGULATORS 

The principal systems of automatic temperature control now in 
use, consist of three essential features; First, an air-compressor, 
-eservoir, and distributing pipes; second, thermostats, which are 



Pig. 166. General System of Wiring a House for Electric Heating. 


placed in the rooms to be regulated; and third, special diaphragm or 
pneumatic valves at the radiators. 

The air-compressor is usually operated by water-pressure in 
small plants and by steam in larger ones; electricity is used in some 
cases. Fig. 167 shows a form of water compressor. It is similar 
in principle to a direct-acting steam pump, in which water under 
pressure takes the place of steam. A piston in the upper cylinder 
compresses the air, which is stored in a reservoir provided for the 
purpose. When the pressure in the reservoir drops below a certain 


199 































190 


HEATING AND VENTILATION 


point, the compressor is started automatically, and continues to 
operate until the pressure is brought up to its working standard. 

A thermostat is simply a mechanism for opening and closing 
one or more small valves, and is actuated by changes in the tempera- 



Fig. 167. Air-Compressor Operated by Wa¬ 
ter-Pressure, Automatically Controlled, 
and Operating to Regulate Temperature 
by Controlling Radiator Valves. 



Fig. 168. Thermostat Controlling Valves 
on Radiators, and Operating through Ex¬ 
pansion or Contraction of Metal Strip E. 


Lure of the air in which it is placed. Fig. 168 shows a thermostat 
m which the valves are operated by the expansion and contraction 
of the metal strip E. The degree of temperature at which it acts 
may be adjusted by throwing the pointer at the bottom one way or 
the other. Fig. 169 shows the same thermostat with its ornamental 


200 



































HEATING AND VENTILATION 


191 


casing in place. The thermostat shown in Fig. 170 operates on 
a somewhat different principle. It consists of a vessel separated into 
two chambers by a metal diaphragm. 

One of these chambers is partially 
filled with a liquid which will boil 
at a temperature below that desired 
in the room. The vapor of the 
liquid produces considerable pres¬ 
sure at the normal temperature of 
the room, and a slight increase of 
heat crowds the diaphragm over 
and operates the small valves in a 
manner similar to that of the metal 
strip in the case just described. 

The general form of a dia¬ 
phragm valve is shown in Fig. 171. 

These replace the usual hand-valves 
at the radiators. They are similar 
in construction to the ordinary 
globe or angle valve, except that 
the stem slides up and down in¬ 
stead of being threaded and run¬ 
ning in a nut. The top of the stem 
connects with a flat plate, which 
rests against a rubber diaphragm. 

The valve is held open by a spring, 
as shown, end is closed by admit¬ 
ting compressed air to the space 
above the diaphragm. 

In connecting up the system, 
small concealed pipes are carried 
frem the air-reservoir to the ther¬ 
mostat, which is placed upon an 
inside wall of the room, and from 
there to the diaphragm valve at 
the radiator. When the temperature of the room reaches the maxi¬ 
mum point for which the thermostat is set, its action opens a small 
valve and admits air-pressure to the diaphragm, thus closing off the 



Fig. 


Thermostat of Pig. 168 in 
Ornamental Casing. 


201 










192 


HEATING AND VENTILATION 


steam from the radiator. When the temperature falls, the thermostat 
acts in the opposite manner, and shuts off the air-pressure from the 
diaphragm valve, at the same time opening a small exhaust which 
allows the air above the diaphragm to escape. The pressure being 
removed, the valve opens and again admits steam to the radiator. 

Diaphragm Motors. Dampers are operated pneumatically in 
a similar manner to steam valves. A diaphragm motor , so called, is 
acted upon by the air-pressure; and this lifts a lever which is properly 
connected to the damper by means of chains or levers, thus securing 
the desired movement. 

Dampers. When mixing dampers are operated pneumatically, 
a specially designed thermostat for giving a graduated movement 



to the damper should be used. By this arrangement the damper 
is held in such a position at all times as to admit the proper proportions 
of hot and cold or tempered air for producing the desired temperature 
in the room with which it is connected. 

Large dampers which are to be operated pneumatically, should 
be made up in sections or louvres. Dampers constructed in this 
manner are handled much more easily than when made in a single 
piece. 

It often happens, in large plants, that there are valves and 
dampers in places which are not easily reached for hand manipula¬ 
tion. These may be provided with diaphragms and connected with 
the air-pressure system for operation by hand-switches or cocks 


202 










HEATING AND VENTILATION 193 

conveniently located at some centra/ point in the basement or boiler 

room. 

Telethermometer. This is a device for indicating on a dial 
at some central point the temperature of various rooms or ducts in 
different parts of a building. A special transmitter is placed in each 
of the rooms and electrically connected with a central switchboard. 
Then, by means of suitable switches, any room may be thrown in 
circuit with the recorder , and the temperature existing in the room 
at that time read from the dial. 



Fig 171. Exterior View, and Section Showing Interior Mechanism of Diaphragm Valve. 


Humidostat. The kumidostat is a device to be placed in one or 
more rooms of a building for maintaining an even percentage of 
moisture in the air. The apparatus consists of two essential parts— 
the humidostat and the humidifier. The former corresponds to the 
thermostat in a system of temperature control, and operates a pneu¬ 
matic valve or other mechanism connected with the humidifier when 
the percentage of moisture rises above or falls below certain limits. 
The operating medium is compressed air, the same as for tempera¬ 
ture control; and the two devices are usually connected with the same 
pressure system. 


203 

































194 


HEATING AND VENTILATION 


The normal moisture of a room is 70 per cent, and should never 
exceed that. In cold weather it will be necessary to reduce the 
amount of moisture somewhat, owing to the “sweating” of walls and 
windows. 

The method of moistening the air will depend somewhat upon 
circumstances. If the air for ventilation is delivered to the rooms at 
a temperature not exceeding 70 degrees, the humidifier is best placed 
in the main air-duct. If the air enters at a higher temperature, the 
humidifier must be located in the same room with the humidostat. 

The moistener or humidifier may be of any one of several forms. 
Where steam heating is used, and where the steam is clean and odor¬ 
less and free from oil from engines, a perforated pipe (or pipes) in the 
air-duct is the simplest and best humidifier. The outlets are properly 
adjusted, and then the humidostat shuts off and lets on the steam 
as required. Sometimes a water spray, particularly of warm water, 
may be used in place of steam. When neither steam jet. nor water 
spray is advisable, an evaporating pan containing a steam coil may 
be used, the humidostat controlling the steam to the coil, and the 
water-level in the pan being kept constant by means of a ball-cock. 

AIR=FILTERS AND AIR-’WASHERS 

In cases where the air for ventilating purposes is likely to contain 
soot or street dust, it is desirable to provide some form of filter for 
purifying it before delivering to the rooms. If the air-quantity is 
small and there is plenty of room between the inlet windows and 
the fan, screens of light cheesecloth may be used for this purpose. 
The cloth should be tacked to light but substantial wooden frames, 
which can be easily removed for frequent cleaning. These screens are 
usually set up in “saw-tooth” fashion in order to give as much sur¬ 
face as possible in the least space. 

Another arrangement, used in case of large volumes of air, 
is to provide a number of light cloth bags of considerable length, 
through which the air is drawn before reaching the heater. These are 
fastened to a suitable frame or partition for holding them open. The 
great objection to filters of this kind is their obstruction to the passage 
of the air, especially when filled with dust, the frequent intervals at 
which they should be cleaned, and the great amount of filtering sur¬ 
face required. 


204 


Main Water Pipe to Heaters - 7 


HEATING AND VENTILATION 


195 



An apparatus which is 

coming quite generally into 

use for this purpose, and 

which does away with the 

d disadvantages noted above, 

1 is the spray filter or air- 

§ washer, one form of which 

> is shown in Fig. 172. Air 

5 enters as indicated, and 

•§ first passes through a tem- 

§ pering coil to raise it above 

:§ the freezing point in win- 

| ter weather; then passes 

£ through the spray-chamber, 

w where the dirt is removed: 

* 

| then through an eliminator 
q for removing the water; 
.g and then through a second 
§ heater on its. way to the 
k fan. 

u 

^ The water is forced 
| through the spray-heads 
£ by means of a small cen- 
3 trifugal pump, either belted 
® to the fan shaft or driven 
S by an independent motor. 

| HEATING AND 
| VENTILATION OF 
I VARIOUS CLASSES 
I OF BUILDINGS 

The different methods 

tb 

£ used in heating and venti¬ 
lation,. together with the 
manner of computing the 
various proportions of the 
apparatus, having been 


205 













































































































196 


HEATING AND VENTILATION 


taken up, the application of these systems to the different classes 
of buildings will now be considered briefly. 

School Buildings. For school buildings of small size, the furnace 
system is simple, convenient, and generally effective. Its use is con¬ 
fined as a general rule to buildings having not more than six or eight 
rooms. For large ones this method must generally give way to some 
form of indirect steam system with one or more boilers, which occupy 
less space, and are more easily cared for than a number of furnaces 
scattered about in different parts of the basement. As in all systems 
that depend on natural circulation, the supply and removal of air is 
considerably affected by changes in the outside temperature and by 
winds. 

The furnaces used are generally built of cast iron, this material 
being durable, and easily made to present large and effective heating 
surfaces. To adapt the larger sizes of house-heating furnaces to 
schools, a much larger space must be provided between the body and 
the casing, to permit a sufficient volume of air to pass to the rooms. 
The free area of the air-passage should be sufficient to allow a velocity 
of about 400 feet per minute. 

The size of furnace is based on the amount of heat lost by radia¬ 
tion and conduction through walls and windows, plus that carried 
away by air passing up the ventilating flues. These quantities may 
be computed by the usual methods for “loss of heat by conduction 
through walls,” and “heat required for ventilation.” With more 
regular and skilful attendance, it is safe to assume a higher rate of 
combustion in schoolhouse heaters than in those used for warming 
residences. Allowing a maximum combustion of 6 pounds of coal 
per hour per square foot of grate, and assuming that 8,000 B. T. U. 
per pound are taken up by the air passing over the furnace, »we have 
6 X 8,000 = 48,000 B. T. U. furnished per hour per square foot of 
grate. Therefore, if we divide the total B. T. U. required for both 
warming and ventilation by 48,000, it will give us the necessary grate, 
surface in square feet. It has been found in practice that a furnace 
with a firepot 32 inches in diameter, and having ample heating surface, 
is capable of heating two 50-pupil rooms in zero weather. The sizes 
of ducts and flues may be determined by rules already given under 
furnace and indirect steam heating. 

The velocity of the warm air within the uptake flues depends 


206 


HEATING AND VENTILATION 


197 


upon their height and the difference in temperature between the 
warm air within the flues and the cold air outside. The action of 
the wind also affects the velocity of air-flow. It has been found by 
experience that flues having sectional areas of about 6 square feet for 
first-floor rooms, 5 square feet for the second floor, and 4J square feet 
for the third, will be of ample size for standard classrooms seating 
from 40 to 50 pupils in primary and grammar schools. These sizes 
may be used for both furnace and indirect gravity steam heating. 

The vent flues may be made 5 square feet for the first floor^and 
6 square feet for the second and third floors. They may be ar¬ 
ranged in banks, and carried through the roof in the form of large 
chimneys, or may be carried to the attic space and there gathered 
by means of galvanized-iron ducts connecting with roof vents of 
wood or copper construction. 

In order to make the vent flues “draw” sufficiently in mild or 
heavy weather, it is necessary to provide some means for warming 
the air within them to a temperature somewhat above that of the 
rooms with which they connect. This may be done by placing a 
small stove made specially for the purpose, at the base of each flue. 
If this is done, it is necessary to carry the air down and connect with 
the flue just below the stove. 

The cold-air supply duct to each furnace should be made J 
the size of all the warm-air flues if free from bends, or the full 
size if obstructed in any way. 

The inlet and outlet openings from the rooms into the flues, are 
commonly provided with grilles of iron wire having a mesh of 2 to 2\ 
inches. Both flat and square wire are used for this purpose. Mixing 
dampers for regulating the temperature of the rooms should be pro¬ 
vided for each flue. The effectiveness of these dampers will depend 
largely upon their construction; and they should be made tight 
against cold-air leakage, by covering the surfaces or flanges against 
which they close with some form of asbestos felting. Both inlet and 
outlet gratings should be provided with adjustable dampers. One of 
the disadvantages of this system is the delivery of all the heat to the 
room from a single point, and this not always in a position to give the 
best results. The outer walls are thus left unwarmed, except as the 
heat is diffused throughout the room by air-current's. When there is 
considerable glass surface, as in most of our modern schoolrooms, 


207 


198 


HEATING AND VENTILATION 


draughts and currents of cold air are frequently found along the out¬ 
side walls. 

The indirect gravity system of steam heating comes next in cost 
of installation. One important advantage of this system over furnace 
heating comes from the ability to place the heating coils at the base 
of the flues, thus doing away with horizontal runs of air-pipe, which 
are required to some extent in furnace heating. The warm-air 
currents in the flues areTess affected by variations in the direction and 
force of the wind where this construction is possible, and this is of 
much importance in exposed locations. 

The method of supplying cold air to the coils or heaters is im¬ 
portant, and should be carefully worked out. The supply should be 
taken from at least two sides of the building, or, if possible, from all 
four sides. When it is taken from four sides, each inlet should be 
made large enough to supply one-half the amount, or, in other words, 
any two should give the total quantity required. It is often possible 
to arrange the flues in groups so that all the heating stacks may be 
placed in two or more cold-air chambers, depending upon the size 
of the building. A cold-air trunk line may be run through the center 
of the basement, connecting with the outside on all four sides, and 
having branches supplying each cold-air chamber. 

Cast-iron pin-radiators are particularly adapted to this class 
of work. 

The School-Pin, having a section about 10 inches in depth and 
rated at 15 square feet of heating surface per section, is used quite 
extensively for this purpose. Stacks containing about 240 square 
feet of surface for southerly rooms, and 260 for those having a nortl> 
erly exposure, have been found ample for ordinary conditions in zero 
weather. 

A very satisfactory arrangement is the use of indirect heaters 
for warming the air needed for ventilation, and the placing of direct 
radiation in the rooms for heating purposes. The general construc¬ 
tion of the indirect stacks and flues may be the same; but the heating 
surface can be reduced, as the air in this case must be raised only to 
70 or 75 degrees in zero weather, the heat to offset that lost by con¬ 
duction, etc., through walls and windows being provided by the 
direct surface. The mixing dampers may be omitted, and the tem¬ 
perature of the room regulated by opening or closing the steam valves 


208 


HEATING AND VENTILATION 


199 


on the direct coils, which should be done automatically. The direct- 
heating surface, which is best made up of lines of 1 J-inch pipe, should 
be placed along the outer walls beneath the windows This supplies 
heat where most needed, and does away with the tendency to draughts. 
In mild weather, during the spring and fall, the indirect heaters may 
prove sufficient for both ventilation and warming. 

Where direct radiation is placed in the rooms, the quantity of 
heat supplied is not affected by varying wind conditions, as is the 
case in indirect heating. Although the air-supply may be reduced 
at times, the heat quantity is not changed. Direct radiation has the 
disadvantage of a more or less unsightly appearance, and architects 
and owners often object to the running of mains or risers through 
the rooms of the building. Air-valves should always be provided 
with drip connections carried to a sink or dry well in the basement. 

When circulation coils are used, a good method of drainage is 
to carry separate returns from each coil to the basement, and to place 
the air-valves in the drops just below the basement ceiling. A check- 
valve should be placed below the water-line in each return. 

The gravity system has the fault of not supplying a uniform 
quantity of air under all conditions of outside temperature, the same 
as a furnace, but when properly arranged, may be made to give quite 
satisfactory results. 

The fan or blower system for ventilation, with direct radiation 
in the rooms for warming, is considered to be one of the best possible 
arrangements. 

In designing a plant of this kind, the main heating coil should 
be of sufficient size to warm the total air-supply to 70 or 75 degrees 
in the coldest weather, and the direct surface should be proportioned 
for heating the building independently of the indirect system. Auto¬ 
matic temperature regulation should be used in connection with 
systems of this kind, by placing pneumatic valves on the direct radia¬ 
tion. It is customary to carry from 3 to 8 pounds pressure on the 
direct system, and from 8 to 15 pounds on the main coil, depending 
upon the outside temperature. The foot-warmers, vestibule, and 
office heaters should be placed on a separate line of piping, with 
separate returns and trap, so that they can be used independently 
of the rest of the building if desired. Where there is a large assembly 
h*jj it should be arranged so that it can be both warmed and venth 


209 


200 


HEATING AND VENTILATION 


lated when the rest of the building is shut off. This can be done by a 
proper arrangement of valves and dampers. 

When different parts of the system are run on different pressures, 
the returns from each should discharge through separate traps into 
a receiver having connection with the atmosphere by means of a vent 
pipe. Fig. 173 shows a common arrangement for the return con¬ 
nections in a combination system of this kind. The different traps 
discharge into the vented receiver as shown; and the water is pumped 
back to the boiler automatically when it rises above a given level in 
the receiver, a pump governor being used to start and stop the pumps 
as required. 

A water-level or seal of suitable height is maintained in the main 
returns, by placing the trap at the required elevation and bringing 
the returns into it near the bottom; a balance pipe is connected with 
the top for equalizing the pressure, the same as in the case of a pump 
governor. Sometimes a fan is used with the heating coils placed at 
the base of the flues, instead of in the rooms. Where this is done 
the radiating surface may be reduced about one-half. This system 
is less expensive to install, but has the disadvantage of removing the 
heating surface from the cold walls, where it is most needed. 

With a blower type of fan, the size of the main ducts may be 
based on a velocity of from 1,000 to 1,200 feet per minute, and the 
branches on a velocity of 800 to 1,000 feet per minute. 

The velocity in the vertical flues may be from 600 to 700 feet per 
minute, although the lower velocity is preferable. 

The size of the inlet registers should be such that the velocity 
of the entering air will not exceed 350 to 400 feet per minute. 

When the air is delivered through a register at the high velocities 
mentioned, some means must be provided for diffusing the entering 
current, in order to prevent disagreeable draughts. This is usually 
accomplished by the use of deflecting blades of galvanized iron, set 
in a vertical position and at varying angles, so that the air is thrown 
towards each side as it issues from the register. The size of the 
vent flues should be about the same as for a gravity system—that is, 
about 6 square feet for a standard classroom, and in the same pro¬ 
portion for smaller rooms. 

Vent-flue heaters are not usually required in connection with a 
fan system, as the force of the fan is sufficient to supply the required 


210 


HEATING AND VENTILATION 


201 



211 

















































































































































202 


HEATING AND VENTILATION 


quantity of air at all times without the aspirating effect of the vent 
flues. 

The method of piping shown in Fig. 173 applies especially to 
buildings of large size. In the case of medium-sized buildings, it 
is often possible to use pin radiation for the main heater, placing the 
same well above the water-line of the boilers and thus returning the 
condensation by gravity, without the use of pumps or traps. When 
this arrangement is used, an engine with a large cylinder should be 
employed, so that the steam pressure will not exceed 15 or 18 pounds, 
and the whole system, including the direct surface, may be run upon 
the same system. 

This is a very simple arrangement, and is adapted to all build¬ 
ings of small and medium size where the heater can be placed at a 
sufficient height above the boilers. 

Temperature control is usually secured automatically by placing 
pneumatic valves upon either the direct or supplementary heaters. 
Mixing dampers are sometimes used instead, in the latter case. Every 
fan system should be provided with a thermometer of large size for 
indicating the temperature of the air in the main duct just beyond 
the fan. 

The ventilation of the toilet-rooms of a school building is a 
matter of the greatest importance. The first requirement is that the 
air-movement shall be into these rooms from the corridors instead of 
outward. To obtain this result, it is necessary to produce a slight 
vacuum within, and this cannot well be done if fresh air is forced 
into them. 

One of the most satisfactory arrangements is to provide exhaust 
ventilation only, and to remove the greater part of the air through 
local vents connecting with the fixtures. 

Hospitals. The best system for heating and ventilating a hos¬ 
pital depends upon the character and arrangement of the buildings. 
It is desirable in all cases to do the heating from a central plant, 
rather than to carry fires in the separate buildings, both on account 
of economy and for cleanliness. 

In the case of small cottage hospitals with two or three buildings 
placed close together, indirect hot water affords a desirable system for 
the wards, with direct heat for the other rooms; but where there are 
several buildings, and especially if they are some distance apart, it 


212 


HEATING AND VENTILATION 


203 


becomes necessary to substitute steam unless the water is pumped 
through the mains. For large city buildings, a fan system is always 
desirable. 

If the building is tall compared with its ground area, so that 
the horizontal supply ducts will be comparatively short,*the double¬ 
duct system may be used with good results. Where the rooms are 
of good size, and the number of supply flues not great, the use of 
supplementary heaters at the bases of the flues makes a satisfactory 
arrangement. Direct radiation should never be used in the wards 
when it can be avoided, even in connection with an independent air- 
supply, as it offers too great an opportunity for the accumulation of 
dust in places which are difficult to reach. 

It is common to provide from 80 to 100 cubic feet ©f air per 
minute per patient in ordinary wards, and from 100 to 120 cubic feet 
in contagious wards. 

The usual ward building of a modern cottage-hospital generally 
contains a main ward having from 8 to 12 beds, and a number of 
private rooms of one bed each. 

In addition to these, there are a diet kitchen, duty-room, toilet- 
rooms, bathrooms, linen-closets, and lockers. 

For moderately sheltered locations, 30 square feet of indirect 
steam radiation has been found sufficient in zero weather for a single 
ward with one exposed wall and a single window, when upon the 
south side of the building. 

For northerly rooms, 40 square feet should be used. In exposed 
locations, the heaters may be made 40 and 50 square feet for north 
and south rooms respectively. The standard pin-radiators rated, at 
10 square feet of heating surface per section, are commonly used for 
this purpose. In case hot water is used, the same number of sections 
of the deep-pin pattern rated at 15 square feet each may be employed, 
making a total of 45 and 60 square feet per room. For corner rooms 
having two exposed walls and two windows, the amount of radiation 
should be increased about 50 per cent over that given above. 

The wards are usually furnished with fireplaces which provide 
for the discharge ventilation. In case the fireplaces are omitted, a 
special vent flue, either of brick or of galvanized iron, should be pro¬ 
vided. These should not be less than 8 by 12 inches for single wards, 
and the equivalent for each bed in a large ward. Each flue of this 


213 


204 


HEATING AND VENTILATION 


kind should have a loop of steam pipe for producing a draught. A 
loop of 1-inch pipe, 10 or 12 feet in height, is usually sufficient for 
this purpose. 

Other rooms than wards are usually heated with direct radia¬ 
tors, the sizes of which may be computed in the same manner as for 
dwelling-houses. 

Steam tables for the kitchen, sterilizers, and laundry machinery, 
require higher pressures than is necessary for heating. 

In large plants the boilers are usually run at high pressure, and 
the pressure reduced for heating. A good arrangement for small 
plants is to provide sufficient boiler power for warming and ventilating 
purposes, and run at a pressure of 3 to 5 pounds. In addition to 
this, a small high-pressure boiler carrying 70 or 80 pounds should be 
furnished for laundry work and water heating. 

Churches. Churches may be warmed by furnaces, by indirect 
steam, or by means of a fan. For small buildings the furnace is 
more commonly used. This apparatus is the simplest of all and is 
comparatively inexpensive. Heat may be generated quickly, and 
when the fires are no longer needed, they may be allowed to go out 
without danger of damage to any part of the system from freezing. 

It is not usually necessary that the heating apparatus be large 
enough to warm the entire building at one time to 70 degrees with 
frequent change of air. If the building is thoroughly warmed before 
occupancy, either by rotation or by a slow inward movement of 
outside air, the chapel or Sunday-school room may be shut off until 
near the close of the service in the auditorium, when a portion of the 
warm air may be turned into it. When the service ends, the switch- 
damper is opened wide, and all the air is discharged into the Sunday- 
school room. The position of the warm-air registers will depend 
somewhat upon the construction of the building, but it is well to keep 
them near the outer walls and the colder parts of the room. Large 
inlet registers should be placed in the floor near the entrance doors,' 
to stop cold draughts from blowing up the aisles when the doors are 
opened, and also to be used as foot-warmers. 

Ceiling ventilators are generally provided, but should be no 
larger than is necessary to remove the products of combustion from 
the gaslights, etc. If too large, much of the warmest and purest 
air will escape through them. The main vent flues should be placed 


214 


HEATING AND VENTILATION 


205 


in or near the floor and should be connected with a vent shaft leading 
outboard. This flue should be provided with a small stove or flue 
heater made specially for this purpose. In cold weather the natural 
draught will be found sufficient in most cases. 

The same general rules are to be followed in the case of 
indirect steam as have been described for furnace heating. The 
stacks are placed beneath the registers or flues, and mixing dampers 
provided. If there are large windows, flues should be arranged to 
open in the window-sills, so that a sheet of warm air may be delivered 
in front of the windows, to counteract the effects of cold down-draughts 
from the exposed glass. These flues may usually be made 3 or 4 
inches in depth, and should extend the entire width of the window. 
Small rooms, such as vestibules, library, pastor’s room, etc., are usually 
heated with direct radiators. Rooms which are used during the 
week are often connected with an independent heater so that they 
may be warmed without running the large boilers, as would otherwise 
be necessary. 

When a fan is used, it is desirable, if possible, to deliver the air 
to the auditorium through a large number of small openings. This 
is often done by constructing a shallow box under each pew, running 
its entire length, and connecting it with the distributing ducts or a 
plenum space by means of a pipe from below. The air is delivered 
at a low velocity through a long slot, as shown in Fig. 174. 

The warm-air flues in the window-sills should be retained, but 
may be made shallower, and the air forced in at a high velocity. 

If the auditorium has a sloping floor, a plenum space may be 
provided between the upper or raised portion and the main floor. 
Sometimes a shallow basement 3 or 4 feet in height, with a cemented 
floor, and extending under the entire auditorium, is used as an air 
or plenum space. 

If -the basement is of good height and used for storage or other 
purposes, it is necessary to carry galvanized-iron ducts at the ceiling 
under the center of each double row of pews, and to connect with 
each pair by means of branch uptakes. The size of these should 
be equal to 3 or 4 square inches for each occupant. 

Another method is to supply the air through a small register in 
the end of each pew. This simplifies the pew construction some¬ 
what, but otherwise is not so satisfactory as the preceding method- 


215 


206 


HEATING AND VENTILATION 


If the special pew construction is too expensive, or for any other 
reason cannot well be used, and the fan is to be retained, the greater 
part of the air is best introduced through wall registers placed about 
8 feet above the floor, with exhaust openings at or near the floor. 
By this arrangement the air is thrown horizontally toward the center 
of the church, and much of it falls to the breathing level without 
rising to the upper part of the room. 

Halls. The treatment of a large audience hall is similar to that 
of a church, the warming being usually done in one of the three ways 
already described. Where a fan is used, the air is commonly delivered 

through wall registers placed in 
part near the floor, and partly at a 
height of 7 or 8 feet above it. They 
should be made of ample size, 
so that there will be freedom from 
draughts. A part of the vents 
should be placed in the ceiling, 
and the remainder near the floor. 
All ceiling vents, in both halls and 
churches, should be provided with 
dampers having means for hold¬ 
ing them in any desired position. 
If indirect gravity heaters are 
used, it will generally be necessary 
to place heating coils in the vent 
flues for use in mild weather; but 
if the fresh air is supplied by 
means of a fan, there will usually be 
pressure enough in the room to force the air out without the aid of 
other means. When the vent air-ways are restricted, or the air is 
impeded in any way, electric ventilating fans-are often used.* These 
give especially good results in warmer weather, when natural venti¬ 
lation is sluggish. The temperature may be regulated either by 
using the double-duct system or by shutting off or turning on a greater 
or less number of sections in the main heater. After an audience 
hall is once warmed and filled with people, very little heat is required 
to keep it comfortable, even in the coldest weather. 

Theaters. Ip designing heating and ventilating systems for 



Fig. 174. An Approved Method of De¬ 
livering Warm Air to the Audi¬ 
torium of a Church. 


216 





















HEATING AND VENTILATION 


207 


theaters, a wide experience and the greatest care are necessary to 
secure the best results. A theater consists of three parts: the body 
of the house, or auditorium; the stage and dressing-rooms, and the 
foyer, lobbies, corridors, stairways, and offices. Theaters are usually 
located in cities, and surrounded with other buildings on two or more 
sides, thus allowing no direct connection by windows with the ex¬ 
ternal air; for this reason artificial means are necessary for providing 
suitable ventilation, and a forced circulation by means of a fan is the 
only satisfactory means of accomplishing this. It is usually advisable 
to create a slight excess of pressure in the auditorium, in order that 
all openings shall allow for the discharge rather than the inward 
leakage of air. 

The general and most approved method of air-distribution is 
to force it into closed spaces beneath the auditorium and balcony 
floors, and allow it to discharge upward through small openings 
among the seats. One of the best methods is through chair-legs 
of special latticed design, which are placed over suitable openings in 
the floor; in this way the air is delivered to the room in small streams, 
at a low velocity, without draughts or currents. The discharge 
ventilation should be largely through ceiling vents, and this may be 
assisted if necessary by the use of ventilating fans. Vent openings 
should also be provided at the rear of the balconies, either in the wall 
or in the ceiling, and these should be connected with an exhaust fan 
either in the basement or in the attic, as is most convenient. 

The close seating of the occupants produces a large amount of 
anirnal heat, which usually increases the temperature from 6 to 10 
degrees, or even more; so that, in considering a theater once filled 
and thoroughly warmed, it becomes more of a question of cooling 
than one of warming to produce comfort. 

The dressing-rooms should be provided with a generous supply 
of fresh-air, sufficient to change the entire contents once in 10 minutes 
at least, and should have discharge flues of sufficient size to carry 
away this amount of air at a velocity not exceeding 300 feet per 
minute, unless connected with an exhaust fan, in which case, the 
velocity may be doubled. The foyer, corridors, dressing-rooms, 
etc., are generally heated by direct radiators, which may be con¬ 
cealed by ornamental screens if desired. 

Office Buildings. This class of buildings may be satisfactorily 


217 


208 


HEATING AND VENTILATION 

warmed by direct steam, hot water, or, where ventilation is desired, 
by the fan system. Probably direct steam is used more frequently 
than any other system for this purpose. Vacuum systems are well 
adapted to the conditions usually found in this type of building, 
as most modern office buildings have their own light and power 
plants, and the exhaust steam can thus be utilized for heating pur¬ 
poses. The piping may be either single or double. If the former 
is used, it is better to carry a single main riser to the upper story, and 
run drops to the basement, as by this means the steam and water 
flow in the same direction, and much smaller pipes can be used than 
would be the case if risers were carried from the basement upward. 

Special provision must be made for the expansion of the risers or 
drops in tall buildings. They are usually anchored at the center, 
and allowed to expand in both directions. The connections with the 
radiators must not be so rigid as to cause undue strains or to lift the 
radiators from the floor. 

It is customary, in most cases, to make the connections with 
the end farthest from the riser; this gives a length of horizontal pipe 
which has a certain amount of spring, and will care for any vertical 
movement of the riser that is likely to occur. Forced hot-water 
circulation is often used in connection with exhaust steam. The 
water is warmed by the steam in larg^ heaters similar to feed-water 
heaters and is circulated through the system by means of centrifugal 
pumps. This has the usual advantage of hot water over steam, 
inasmuch as the temperature of the radiators may be regulated to 
suit the conditions of outside temperature. 

When a fan system is used the arrangement of the air-ways is 
usually somewhat different from any of those yet described. Owing 
to the great height of these buildings, and the large number of small 
rooms which they contain, it is impossible to carry up separate flues 
from the basement. One of the best arrangements is to construct 
false ceilings in the corridor-ways on each floor, thus forming air- 
ducts which may receive their supply through one or more large up¬ 
takes extending from the basement to the top of the building. These 
corridor air-ways may be tapped over the door of each room, the 
openings being provided with suitable regulating dampers for gauging 
the air-supply to each. Adjustable deflectors should be placed in 
the main air-shafts for proportioning the quantity to be delivered 


218 


HEATING AND VENTILATION 


209 


to each floor. If both supply and discharge ventilation are to be 
provided, the fresh air may be carried in galvanized-iron ducts within 
the ceiling spaces, and the remainder used for conveying the exhausted 
air to uptakes leading to a discharge fan placed upon the roof of 
the building. In both of these cases, it is assumed that heat is sup¬ 
plied to the rooms by direct radiation, and that the air-supply is for 
ventilation only. 

Apartment Houses. These are warmed by furnaces, direct 
steam, and hot water. Furnaces are more often used in the smaller 
houses, as they are cheaper to install, and require a less skilful at¬ 
tendant to operate them. Steam is probably used more than any 
other system in blocks of larger size. A well-designed single-pipe 
connection, with autcmatic air-valves dripped to the basement, is 
probably the most satisfactory in this class of work. People who 
are more or less unfamiliar with steam systems are apt to overlook 
one of the valves in shutting off or turning on steam; and where only 
one valve is used, the difficulty arising from this is avoided. Where 
pet-cock air-valves are used, they are often left open through careless¬ 
ness ; and the automatic valves, unless dripped, are likely to give more 
or less trouble. 

Greenhouses and Conservatories. Buildings of this class are 
heated in some cases by steam-and in others by hot water, some florists 
preferring one and some the other. Either system, when properly 
designed and constructed, should give satisfaction, although hot 
water has its usual advantage of a variable temperature. The 
-methods of piping are, in a general way, like those already described, 
and the pipes may be located to run underneath the beds of growing 
plants or above, as bottom or top heat is desired. The main is gen¬ 
erally run near the upper part of the greenhouse and to the farthest 
extremity, in one or more branches, with a pitch upward from the 
heater for hot water and with a pitch downward for steam. The 
principal radiating surface is made of parallel lines of 1J inch or 
larger pipe, placed under the benches and supplied by the return 
current. Figs. 175, 17G, and 177 show a common method of running 
the piping in greenhouse work. Fig. 175 shows a plan and eleva¬ 
tion of the building with its lines of pipe; and Figs. 170 and 177 give 
details of the pipe connections of the outer and inner groups of pipes 
respectively. 


219 


210 


HEATING AND VENTILATION 


Any system of piping which gives free circulation and which is 
adapted to the local conditions, should give satisfactory results. The 
radiating surface may be computed from the rules already given. 
As the average greenhouse is composed almost entirely of glass, we 


Fig. 175. 



Plan and Elevation Showing One Method of Running Piping in a Greenhouse 


may for purposes of calculation consider it such; and if we divide 
the total exposed surface by 4, we shall get practically the same 
result as if we assumed a heat loss of 85 B. T. U. per square foot of 
surface per hour, and an efficiency of 330 B. T. U. for the heating 


220 

































































HEATING AND VENTILATION 


211 


coils; so that we may say, in general, that the square feet of radiating 
surface required equals the total exposed surface, divided by 4 for 
steam coils, and by 2.5 for hot-water. These results should be in¬ 
creased from 10 to 20 per cent for exposed locations. 

CARE AND MANAGEMENT 

The care of furnaces, hot-water heaters, and steam boilers has 
been discussed in connection with the design of these different systems 
of heating, and need not be repeated. The management of the 
heating and ventilating systems in large school buildings is a matter 
of much importance, especially in those using a fan system. To obtain 
the best results, as much depends upon the skill of the operating 
engineer as upon that of the designer. 

Beginning in the boiler-room, he should exercise special care 
in the management of his fires, and the instruction given in “Boiler 
Accessories” should be carefully followedall flues and smoke 
passages should be kept clear and free from accumulations of soot 
and ashes by means of a brush or steam jet. Pumps and engine should 
be kept clean and in perfect adjustment, and extra care should be 
taken when they are in rooms through which the air-supply is drawn, 
or the odor of oil will be carried to the rooms. All steam traps should 
be examined at regular intervals to see that they are in working order; 
and upon any sign of trouble, they should be taken apart and care¬ 
fully cleaned. 

The air-valves on all direct and indirect radiators should be 
inspected often; and upon the failure of any room to heat properly, 
the air-valve should first be looked to as a probable cause of the diffi¬ 
culty. Adjusting dampers should be placed in the base of each flue, 
so that the flow to each room may be regulated independently. In 
starting up a new plant, the system should be put in proper balance 
by a suitable adjustment of these dampers; and, when once adjusted, 
they should be marked, and left in these positions. The temperature 
of the rooms should never be regulated by closing the inlet registers. 
These should never be touched unless the room is to be unused for 
a day or more. 

In designing a fan system, provision should be made for air - 
roiation ; that is, the arrangement should be such that the same 
air may be taken from the building and passed through the fan and 


221 


212 


HEATING AND VENTILATION 




Fig. 177. Connections of Inner Groups of Pipes of Greenhouse Shown in Fig. 175. 


222 


































HEATING AND VENTILATION 


213 


heater continuously. This is usually accomplished by closing the 
main vent flues and the cold-air inlet to the building, then opening the 
class-room doors into the corridor-ways, and drawing the air down 
the stair-wells to the basement and into the space back of the main 
heater through doors provided for this purpose. In warming up a 
building in the morning, this should always be done until about 
fifteen minutes before school opens. The vent flues should then be 
opened, doors into corridors closed, cold-air inlets opened wide, and 
the full volume of fresh air taken from out of doors. 

At night time the dampers in the main vents should be closed, 
to prevent the warm air contained in the building from escaping. 
The fresh air should be delivered to the rooms at a temperature of 
from 70 to 75 degrees; and this temperature must be obtained by 
proper use of the shut-off valves, thus running a greater or less number 
of sections on the main heater. A little experience will show the 
engineer how many sections to carry for different degrees of outside 
temperature. A dial thermometer should be placed in the main 
warm-air duct near the fan, so that the temperature of the air delivered 
to the rooms can be easily noted. 

The exhaust steam from the engine and pumps should be turned 
into the main heater; this will supply a greater number of sections 
in mild weather than in cold, owing to the less rapid con¬ 
densation. 


223 
























MANAGEMENT OF DYNAMO- 
ELECTRIC MACHINERY 

PART I 


The object of this treatise is to set forth the most important 
features which must be considered in the actual handling and 
operation of electric generators and motors. The principles and 
general construction of direct-current (d.c.) and alternating-cur¬ 
rent (a. c.) generators and motors are treated elsewhere. The 
subject may be divided into three parts, as follows: 

(1) Selection, Erection, Connection, and Operation 

(2) Inspection and Testing 

(3) Troubles, or “Diseases,” and Remedies. 

THE MACHINE—FROM SELECTION TO SERVICE 

SELECTION OF A MACHINE 

The voltage, capacity, and type of machine are dependent 
upon the system to which it is to be connected and the purpose 
for which it is to be utilized, but there are certain general fea¬ 
tures which should be considered in every case. 

Construction. The construction should be of the most solid 
character and guaranteed first-class in every respect, including 
materials and workmanship. 

Finish. A good finish is desirable, since it is likely to cause 
the attendant to take greater care of the equipment. 

Simplicity. The machine should be as simple as possible in 
all its parts; peculiar or complicated features should be avoided, 
unless absolutely essential for the operation of the system. 

Attention. The amount of attention required by a machine 
depends in a great measure on the kind of machine. Direct-con¬ 
nected revolving-field a. c. generators, revolving-field synchronous 
motors, and induction motors require little or no attention, 


225 



2 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

whereas machines of the commutating type demand a certain 
amount of care to keep brushes and commutators in condition. 
Above all, cleanliness is essential to the life and proper operation 
of all electrical apparatus. 

Handling. Machines of the revolving-field alternating-cur¬ 
rent type are arranged so that the armatures may be moved on 
the foundation plates parallel to the shaft to allow of repairs 
to either field or armatures. Direct-current types of machines 
are usually split through the magnet frame in a horizontal plane 
So that they may be disassembled readily. 

Regulation. Unless the machine is self-regulating, it is usu¬ 
ally customary to employ some automatic device external to the 
machine to maintain constant voltage. 

Form. Preferably the machine should be of standard reli¬ 
able make, to insure proper symmetry of form as well as rug¬ 
gedness of design. 

Capacity. A machine should be carefully selected for the 
work it has to perform, the highest efficiency being obtained at 
normal and slight overloads. The heating at normal and pre¬ 
scribed overloads is fixed by the Standardization Rules of the 
American Institute of Electrical Engineers. 

Cost. It is usually an error to select a generator or motor 
simply because it is cheap, since both the materials and the work¬ 
manship required for the construction of a high-grade electrical 
machine are costly. 


ERECTION 

MECHANICAL CONDITIONS 

Location. The place chosen for the machine should, if possi¬ 
ble, be dry, free from dust or grit, light, and well ventilated . It 
should also be arranged so that there is room enough for the removal 
of the armature without shifting or turning the machine. 

Foundations. It is of great importance to have the machine 
firmly placed upon a good and solid foundation; otherwise, no 
matter how well constructed and well managed, the vibrations 
occurring on a poor foundation will produce noise, sparking at the 
brushes, and other troubles. 


226 


MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 3 


It is also necessary, if the machine is belt-driven, to mount 
it upon rails or a sliding bed-plate provided with holding-down 
bolts and tightening screws for aligning and adjusting the belt 
while the machine is in operation,‘Fig. 1. The machinery founda¬ 
tions consist of a mass of stone, masonry, brickwork, or concrete, 
upon which the machinery is placed and usually held firmly in 
place by bolts passing entirely through the mass. These bolts are 
built into the foundations, the proper positions for them being 
determined by a wood template suspended above the foundation, 





Fig. 1. General Electric Belted Generator Showing Adjustable Base 

as shown in Fig. 2. The bolts are preferably surrounded by iron 
pipe that fixes them longitudinally but allows a little side play 
which may be necessary to enable them to enter the bed-plate holes 
readily. The brickwork for machinery foundations should consist 
of hard burned bricks of first quality, laid in good cement mortar. 
Lime mortar is entirely unfit for the purpose, being likely to crum¬ 
ble away under the effect of the vibrations caused by the machin¬ 
ery. Brick or concrete foundations should be finished with a cap 
of cement. This forms a level surface upon which to set the 


227 


4 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

machinery. Almost all large foundations are concrete, brick seldom 
being used. 

Fixing the Machine. Levelling . In fixing either direct-con¬ 
nected or belt-driven machines, determine, with a long straight edge 
and spirit level, checked by a surveyor’s Y level, if the top of the 
foundation is level and true. If this is found to be the case, the 
holding-down bolts may be dropped into the holes in the founda¬ 
tion, if they are not already built in, and the machine carefully 
placed thereon, the ends of the bolts being passed through the 
holes in the bed-plate and secured by a few turns of the nuts. 



Fig. 2. Diagram of Power House Foundation Showing Wood Template Suspended 
above Foundation for Construction Purposes 


Aligning. The machine should then, if belt-connected, be 
carefully aligned with the transmitting pulley or flywheel. Par¬ 
ticular attention should be paid to the alignment of the pulleys 
m order that the belt may run properly. If direct-connected, 
the dynamo bed-plate and armature shaft must be carefully 
aligned and adjusted with respect to the engine shaft, raising or 
lowering the bed-plates of the corresponding machines by means 
of thin cast iron or other wedges; and the generator frame also 
should be adjusted to its proper height by means of thin strips 
of metal set between its supporting feet and the bed-plate. 


228 





























































MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 5 

Grouting the Base . Having thus aligned and leveled the ma¬ 
chine, it should next be grouted with thin cement. This is done 
by arranging a wall of mud or wood battens around the bed-plates 
of the machine, and running in thin cement until the holding- 
down bolt holes are filled, and the cement has risen at least one- 
! half inch above the under side of the bed-plate. This head of 
; grouting allows for shrinkage as the water dries and the grouting 
settles. If grouting were poured only to the under side of the bed¬ 
plate, it would shrink away when dry and leave a space between the 
foundation and the bed-plate. When the cement has partially set, 
the wall may be taken down and the surplus cement removed. 
When the cement is dry, the nuts on the holding-down bolts may be 
drawn up. This fixes the machine firmly upon its foundation. 

Mechanical Connections 

Various means are employed to connect the engine or other 
prime mover with the generator, or the motor with the apparatus 
to be driven. The most important are as follows: 

Direct Connection Rope Driving 

Belting Toothed Gearing 

| Other apparatus, such as shafting, clutches, hangers, and pulleys, 

| are used in combination with the above means. 

Direct Connection. Direct connection is the simplest and, 
for that and other reasons, the most desirable means of connection, 
provided it can be carried out without involving sacrifices that off¬ 
set its advantages. This method, also called direct coupling or 
direct driving, compels the engine and the generator to run at the 
same speed, which gives rise to some difficulty, as the most desirable 
speeds of the two machines do not usually agree. The natural 
speed of a generator is high, while that of a reciprocating engine is 
low; hence to obtain the same voltage from a direct-connected 
generator, more conductors are necessary, or the flux cut must be 
increased. Accordingly, the armature and the frame of the direct- 
connected generator must be larger, thus making it more expensive 
than a belt-driven machine. On the other hand the speed of steam 
turbines is so high that it usually requires specially designed and 
constructed generators for direct connection. 


229 




6 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


Continuous Shaft for Engine and Generator. The direct con¬ 
nection of an engine and generator is accomplished in several 
ways, the simplest of which consists in mounting the armature 
of the generator directly on one end of the shaft of the engine. 
This may be accomplished in any one of several ways. Fig. 3 
represents a three-bearing belted generator. 

Coupled Shafts. Another form of direct coupling is that in 
which a motor and a generator, each complete in itself, and each 
having two bearings, are coupled together by some mechanical 
device, which may be either rigid or slightly elastic or adjustable. 


Fig. 3. Fort Wayne Three-Bearing Belted Generator. 

In the former case the two shafts are practically equivalent to a 
single one, which, while making it easy to remove either machine 
for repairs, is-somewhat objectionable owing to the fact that it 
requires larger foundations and introduces the difficulty of accu¬ 
rately aligning four bearings. The use of a flexible coupling 
avoids the necessity of perfect alignment, and also the serious 
trouble that might arise if the settling or the wear of the bearings 
should be uneven. There are various forms of flexible coupling, 
one form having rubber cylinders interposed between the two parts. 

1 he direct coupling of generators with hydraulic turbines can 


230 






MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 7 

usually be carried out without departing, from the natural speed 
of either machine, since the ordinary speed of a turbine agrees 
closely with the normal speed of a generator of the corresponding 
capacity. 

The relative efficiency of direct coupling and belting depends 
greatly upon the conditions; but in general the former is more 
efficient at or near rated load, and the latter at light loads. The . 
simplicity , compactness, and positive as well as noiseless action of 
direct connection have caused it to become the most approved' 
method. 

Belting. Kind. If the generator or motor is not directly ( 
connected—the former to the prime mover, the latter to the appara¬ 
tus to be driven—it is usually connected by some form of belting. 
The kind of belting selected depends greatly upon conditions of 
drive, distances, etc., and it may be leather, rawhide, rubber, or 
rope. For the ordinary short drives, leather is the most desirable, 
though, when the power to be transmitted is small, rawhide belts 
are also satisfactory, especially as the cost is less than for leather 
belts. For considerable distances, rope driving answers very well, 
because it is so much lighter and cheaper than an equivalent leather 
belt, though grooved pulleys are required, making the total cost 
about the same. Rubber belts are used to advantage in driving 
generators from water turbines, where the belt might be exposed to 
moisture. Leather belting is usually the most reliable and satis¬ 
factory for general application, except for very short drives, where 
a form of chain belt works best. There are three thicknesses of 
leather belting: single, light-double, and double. For use in con¬ 
nection with generators, motors, or other high-speed machinery, 
the ‘ 1 light-double ’ * belting is usually the best. 

Power Transmitted by Belt. The exact amount of power that 
a given belt is capable of transmitting is not very definite. The 
ordinary rule is that “single” belt will transmit one horsepower 
for each inch of its width when traveling at a speed of 1000 feet 
per minute. If the speed is greater or less, the power is propor¬ 
tionately increased or decreased. This statement of h.p. trans¬ 
mitted is based upon the condition that the belt is in contact with 
the transmitting pulley around one-half of its circumference, or 
180 degrees, which is usually the case. If the arc of contact is less 


231 


8 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


than 180 degrees, the power transmitted is less in the following 
proportion: An arc of 135 degrees gives 84 per cent, while 90 
degrees contact gives only 64 per cent of the power derived from 
a belt contact of 180 degrees. If, on the other hand, the upper side 
sags downward, which is always desirable, the belt is in contact 
with more than half the circumference of the pulley; and thus 
the grip is considerably increased and more power can be trans¬ 
mitted. These facts make it very desirable to have the loose side 
of the belt on top. If the loose side is below, it sags away from 
the pulley and is also likely to strike the floor. 

An approximate expression for determining the width of a 
single belt required to transmit a given horsepower is.as follows: 

w_ h.p. x 1^00 

• W ~ JSxC 


in which W is the width of the belt in inches; h.p. the horsepower 
to be transmitted; S is the speed of the belt in feet per minute, 
which is equal to the circumference of the driving pulley in feet 
multiplied by the number of.revolutions per minute; and C is a 
factor dependent upon the arc of contact.* 

“Double” belting is expected to transmit 1J, and “light- 
double” 1| times as much power as “single” belting of the same 
width. Belting formulas are only approximate and should not 
be applied too rigidly, since the grip of the belt upon the pulley 
varies considerably under different conditions of tension, tempera¬ 
ture, and moisture. The 
smooth side of a belt should 
always be run against a pul¬ 
ley, as it transmits more 
power and is more durable. 

Spliced Joints. Belting 
used for electric machinery, 
being usually high-speed, 
should be made “endless” 
for permanent work, as this makes less noise; but it may be used 
with laced joints temporarily. A spliced or ‘ ‘ endless ’* joint is made 



Fig. 4. Belt Clamp for Splicing 


* Belts slip or “creep” on the pulley about 2 per cent; hence, in determining 
the size of pulleys whose speed must be accurate, the calculated belt speed should be 
about 2 per cent too high. 


232 







MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 9 


as follows: The two ends of the belt are pared down on opposite 
sides with a sharp knife into the form of long thin wedges, so that 
when laid together a long uniform joint is obtained of the same 
thickness as the belt itself. The parts are then firmly joined with 
cement and sometimes with rivets also. It may be necessary to 
splice or lace a belt while in position on the pulleys; and for 
this purpose some form of belt clamp, Fig. 4, should be employed. 

If a belt is ordered endless, or is spliced away from the pul¬ 
leys, great care should be exercised in determining the exact length 
required. A string that will not stretch, or preferably a wire put 
around the pulleys in the position to be occupied by the belt, is 
the best way to avoid a mistake. In measuring for a belt, the 
generator or motor should be moved on its sliding base so as to 
make the distance between shaft centers a minimum, in order 



Fig. 5. Diagram Showing Proper Way of Lacing Belt 


to allow for the stretch of the belt, which may be as much as 
one-half inch per foot of length. 

Laced Joints. The lacing of a belt is a very simple and 
common method of making a joint; but it should not be perma¬ 
nently employed at high speeds for electric machinery belting, as 
it is liable to pound on the pulleys, producing noise, vibration, 
and sparking; with lighting generators it is also likely to cause 
flickering in the lamps. In lacing belts, the ends should be cut 
perfectly square, and there should be as many stitches of the lace 
slanting to the left as there are to the right; otherwise the ends of 
the belt will shift sidewise, owing to the unequal strain, and the 
projecting corners may strike or catch in the clothing of persons. 
A good way to accomplish this is shown in Fig. 5. The various 
holes should be made with a circular punch, the nearest one being 


233 









10 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

about three-fourths inch from the side, and the line through the 
center of the row of holes about one inch from the end of the belt. 
In large belts these distances should be a little greater. A regular 
belt lacing of strong pliable leather or a special wire should be 
used. The lacing is doubled to find its middle; and the ends are 
passed through the two holes marked 1 and la, precisely as in 
lacing a shoe. The two ends are then passed successively through 
the two series of holes, in the order in which they are numbered, 
2, 3, 4, etc., and 2a, 3a, \a, etc., finishing at 13 and 13a, which are 
additional holes for securing the ends of the lace. The great 
advantage of this method of lacing is that the lace lies on the 
pulley side parallel to the direction of motion. 

Arrangement and Care of Belting. It is desirable, for satis¬ 
factory running, that belts should be reasonably long and nearly 
horizontal. The distance between centers of two belt-connected 
pulleys should, if possible, be not less than three times the diameter 
of the larger pulley. The belt should be just tight enough to avoid 
slipping, without straining ‘the shaft or bearings. The two shafts 
which are to be belt-connected must be perfectly parallel, and the 
centers of the faces of the driving and driven pulleys must be 
exactly opposite to each other, in a straight line perpendicular to 
the axis of the shafts. The machines should then be turned over 
slowly with the belt on, to see if the latter tends to run to one 
side of the pulley, which would show that it is not yet properly 
“lined up,” in which case one or both machines should be slightly 
shifted, until the belt runs true. If possible, the machine and the 
belt should be set and adjusted so as to cause the armature to 
move back and forth in the bearings while running, on account of 
the side motion of the belt, and thus make the commutator wear 
more smoothly, and distribute the oil in the bearings. Where it is 
impracticable to have sufficient distance between centers of belt- 
connected pulleys, an idler pulley is often used to give greater arc 
of contact and elastic tension. 

It is always desirable to have belts as pliable as possible; 
hence the occasional use of a good belt dressing—as neatsfoot oil, 
etc.,—is recommended. Rosin and other sticky substances are some¬ 
times applied to increase the adhesion; but this is a practice 
allowable only in an emergency, as it may destroy the belt surface. 


234 


MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 11 


In places where the belting irj very much exposed, and liable 
to catch in the clothing, it is advisable to surround it by a railing 
or box. 

Rope Driving. Rope driving possesses advantages over ordi¬ 
nary belting in some cases. The rope runs in V-shaped grooves in 
the peripheries of the pulleys, and thereby obtains a good grip by a 
sort of wedging action. The kinds of rope ordinarily employed 
for this purpose are cotton, hemp, rawhide, and wire. 

Advantages. The general advantages are as follows: 

(1) Economy in first cost. 

(2) Large amount of power that can be transmitted with a 
given diameter and width of pulley, on account of the grip 
obtained. 

(3) i It is almost noiseless. 

(4) Ropes, on account of their lightness, can be used to trans¬ 
mit power over greater distances than are possible with any other 
form of belting; and also for very short distances on account of 
the wedging action. Manila rope is generally used in the United 
States, being of three strands, hawser laid, and may be from \ 
inch to 2 inches in diameter. The breaking strength varies from 
7000 to 12,000 pounds per square inch of cross section. It has 
been found that the best results are obtained when the tension in 
the driving side of the rope is only 3 to 4 per cent of the breaking 
strength. 

Power Transmitted ~by Pope Drive. The diameter of a single 
rope necessary to transmit a required h.p. is given by the formula: 


825 h.p. 



in which h.p. is horsepower transmitted; V is velocity of rope in 
feet per second; and D is diameter of rope in inches. 

The maximum power is obtained at a speed of about 84 feet 
per second. With higher speeds the centrifugal force becomes so 
great that the power transmitted decreases rapidly, and at about 
142 feet per second it counteracts the whole allowable tension 
(200 D 2 pounds) and no power is transmitted. 

Arrangement of Pope Belting. There are two methods of 
arranging rope transmission: one consists in using several sep¬ 
arate belts; and the other employs a single endless rope which 


235 










12. MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

Table I 

Horsepower Transmitted by Cold=RoIIed Shafting at Various Speeds 


R d 3 in which R is revolutions per minute and d is diametei 

“ 100 of shaft in inches. 


Diameter 
in Inches 

Revolutions per Minute 

100 

200 - 

300 

400 

1* 

3.4 

6.7 

10 

13.5 

n 

4.3 

8.6 

12.8 

17 

it 

5.4 

10.6 

16 

21 

* ii» 

7.3 

14.5 

22 

29 

2 

8 

16 

24 

31.9 

2£ 

9.6 

19.1 

29 

38 

21 

11.4 

23 

34 

45 

3 

27 

54 

81 

108 

31 

34 

68 

103 

136 

3i 

43 

86 

129 

171 

4 

64 

128 

192 

255 

5 

125 

250 

375 

500 


For h.p. transmitted by turned-steel shafting multiply above figures by 0.8. 

For ordinary line shafting with supporting bearings about 8 feet apart— 
multiply by 1.43 for cold-rolled and by 1.11 for turned shafts. 

Usual speed of shafting: 

Machine Shops.120 to 250 r.p.m. 

Wood Shops.250 to 300 r.p.m. 

Textile Mills.300 to 400 r.p.m. 

passes spirally around the pulley several times and is brought 
back to the first groove by a slanting idle pulley, and therefore is 
called the “wound” system. The separate ropes do not require 
the carrying-over pulley and, if one rope breaks, those remaining 
are sufficient to transmit the power temporarily; whereas an acci¬ 
dent with the single-rope system entirely interrupts the service. 
In the “multi-rope” system it is practically impossible to make 
and maintain the belts of exactly equal length, hence the tensions 
on the various ropes differ, and they hang at different heights on 
the slack side, producing an awkward appearance. 

Toothed Gearing. Toothed gearing possesses the decided 
advantages of positive action and the ability to give large ratios of 
speed and small side pressure on the bearings. Nevertheless it is 
seldom employed for driving generators. The most extensive 


236 














MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 13 

applications of gearing for electrical purposes are in connection 
with railway motors, and many industrial applications of a. c. and 
d. c. motors. 

Shafting. An intermediate or countershaft is not desirable 
since it increases the complication and the frictional losses of the 
system; but it is often necessary in the generation or application 
of electric power, either to obtain a greater multiplication of speed 
than is possible by belting directly, or to enable a single engine or 
motor to drive a greater number of machines. 

The two important kinds of shaftings are ‘‘cold-rolled’’ and 
“turned”. The former is rolled to the exact size and requires no 
further treatment. It has the advantage of a smooth hard surface, 
but it is difficult to make it perfectly true and straight. Turned- 
steel shafting is most commonly employed, and has the advantage 
that shoulders, journals, or other variations in size can easily be 
made on it. Table I gives the ordinary data for shafting. 


ASSEMBLING OF THE MACHINE 

Numbers of Parts and Drawings the Guide. The proper 
method of setting the foundation plate, or base, of a machine has 
already been described. The successive parts of the machine 
should then be assembled in their respective order. The bearing 
pedestals will usually be found to have a number stamped on 
them with a corresponding number stamped on the base. The' 
same is true for the magnet frame. Approved drawings showing 
the correct mechanical assembly and proper electrical connection 
should be furnished with each machine. 

Care of Windings. In handling the parts of the machine, 
care must be used not to damage the windings in any way. In 
the case of a direct-current machine, the commutator must be 
properly protected. If the machine is assembled by means of a 
crane, the lifting cable should not come in contact with any part 
of the windings. Often a wood spreader, Fig. 6, between turns of 
the cable is necessary to keep it clear of the windings. 

Attention to Joints and Metal Surfaces. All magnetic joints 
must be made clean and bright. A very light coating of oil will 


237 


14 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

prevent such joints from rusting. The same precaution should 
apply to all finished surfaces about the machine. The bearings 
should be carefully examined to see that their bearing surfaces 
have not been bruised or roughened. Should such defects show 
up, the bearings should be scraped by an experienced machinist. 
If the bearing surface of the shaft has become bruised or pitted by 
rust, this should be carefully smoothed before assembling the shaft 
in the’ bearings. The oil bearings should be flushed out with 
gasoline or some light grade of oil before being filled with a good 



Fig. 6. Proper Rigging for Handling Armature Showing Wood Spreader to 
Protect Windings 

grade of dynamo oil. The field frame should be set so as to obtain 
a uniform air gap all around. 

Brushes and Commutator on D.C. Machines. In the case of 
a direct-current machine the accurate spacing and setting of the 
brushes on the commutator is essential to good commutation. 
Brushes should be fitted to the commutator by drawing a piece of 
sandpaper under them; then they should be spaced around the • 
commutator by laying off on a thin steel tape or a piece of paper 
equidistant positions corresponding to the number of poles on the 
machine. The steel tape is placed around the commutator and 
either the heel or toe of the brushes on each brush stud made to 
conform to the marking on the tape. At the same time the 


238 
























MANAGEMENT OP DYNAMO-ELECTRIC MACHINERY 15 

I' brashes of each set must be placed on the commutator parallel to 
j the commutator bars. 

Examination Before Starting'. Before starting a machine it 
i should be carefully examined to see that there are no loose pieces 
of metal or other material about the machine. See that the bear¬ 
ings are filled with oil to the proper level. If the machine is belt 
I driven, see that the belt has the proper tension. 

Starting a Generator. Gradual Building-Up of Speed. In 
the case of a generator direct-connected to the prime mover, bring 
up the speed of the set gradually. Be sure that everything is 
running smoothly and that the oil rings in the self-oiling bearings 
are turning. The speed may finally be brought up to normal. 
If it has been determined by insulation test that the machine 
requires no drying out, the voltage may be built up to normal 
gradually, and the machine will be ready for regular service. 

! Drying Out % Large direct-current generators often require 
drying out before putting in service. This may be accomplished 
by short circuiting the armature leads beyond the ammeter and 
“bucking” the shunt and series fields. In the case of an alter¬ 
nator, the phases may be short circuited on the outside of the 
switchboard instruments so that a reading may be obtained. The 
field will require very slight excitation to produce full load current 
with phases short circuited. 

Insulation Resistance Test . The insulation resistance should 
be measured and, if this is found to be the proper amount for 
the machine under consideration, it may be put into service. If no 
direct reading instrument is obtainable, the resistance may be 
measured by using a direct-current voltmeter of known high 
resistance on a 500 volt direct-current circuit. The method is as 
follows: 

Using a constant potential of about 500 volts, the voltage 
reading is determined by connecting the terminals of the supply 
circuit directly to the meter. The insulation resistance to be meas¬ 
ured is then connected in series with the voltmeter and a second 
reading is made and noted. The resistance A is then given by the 
formula 

R m D m 

. R m + X = V 


239 




16 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


or 



m 


in which R m is resistance of voltmeter; D m is deflection of volt¬ 
meter with resistance in series; V .is voltage of the supply system 
when reading D m ; and X is resistance sought. 


TYPICAL WIRING CONNECTIONS 


DIRECT=CURRENT GENERATORS 


Shunt Type, Supplying Constant-Potential Circuit. A shunt 

type d. c. generator is represented in Fig. 7, with the necessary 
connections. The brushes are connected to the two conductors 
forming the main circuit; also to the field-magnet coils 8 h through 


a resistance-box R, to regulate 
the strength of the current and, 
therefore, the magnetism in the 
field. A voltmeter also is con¬ 
nected to the two brushes or 
main conductors to measure the 





Fig ' 7 ' Type S o a f m D f °c Generator® Shunt v0 ^ ta ^ e or electrical pressure 

between them. One of the main 
conductors is connected through an ammeter A, which measures 
the total current on the main circuit. The lamp L, or motor M, 
are connected in parallel between the main conductors or between 
branches from them. This represents the ordinary low-tension 
system for electric light and power distribution from isolated 
plants or central stations. 

Series Type. In a series-wound dynamo, the winding on the 
field being in series with the armature, the number of ampere 
turns in the field varies with the load on the machine or the 
amount of current flowing. 

The field is wound with relatively few turns of large wire 
capable of carrying the full armature current. The voltage of a 


240 














MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 17 

series generator is low at light loads, but increases rapidly as load 
comes on. At normal load the field approaches the saturation 
point. Series generators are seldom, if ever, used except for con¬ 
stant-current generators on some arc-lighting systems or for 
boosters. Fig. 8 shows a series generator in which the load, field, 
and armature are all in series. 

Compound Type. A com¬ 
pound-wound generator has two 
sets of field windings—*a shunt 
winding and a series winding— 
and is therefore a combination 
of the two preceding types, 

Fig. 9. At no load and light 
load the shunt field Sli is excited to give normal voltage. The 
series winding S is connected to assist the shunt field so that, as 
the load comes on and a larger current passes through the series 
field, the drop in voltage which would otherwise occur is prevented. 
The voltage at no load is adjusted by means of the rheostat R in 


-F 



* Fig. 9. Diagram for Compound-Wound Generator 


series with the shunt field. As the load comes on, the voltage is 
automatically regulated by the action of the series field. The 
voltage may be held practically constant from no load to full load 
or it may be increased at full load to 10 per cent or 15 per cent 
above the no-load value. This is the usual practice in generators 
for railway work and is called “overcompounding.” 

The adjustment of the compounding is obtained by connecting 
a resistance Z, known as a series-field shunt, across the terminals 



Fig. 8. Diagram for Series Generator 
Showing Load, Field, and Armature, 
All in Series 


241 














18 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


of the series field. The relative value of the resistance of the 
series field and its shunt resistance determines the current in 
the series field, and by adjusting the shunt resistance any desired 
value of compounding may he obtained. 

Direct-Current Generators in Parallel. Successful parallel 
operation of direct-current generators requires that corresponding 
polarities be connected together. The currents of the various 
generators will be added and may have different values, but the 
voltage will not be increased. At the time the machines are con¬ 
nected together, the voltages should be equal, to avoid any undue 
disturbances on the system. 

Shunt-Wound Generators in Parallel . The connection of 
shunt-wound generators to switchboard buses is shown in Fig. 10. 

The machine with its main 
switch closed is operating on 
the station bus, the other gen¬ 
erator is brought up to exactly 
the same voltage and its main 
switch is closed. The voltage 
on this second machine is then 
raised by means of the shunt- 
field rheostat until the generator 
takes its proportion of the load. 
Assume the two generators to 
be of the same rating and volt¬ 
age, and each, therefore, supply¬ 
ing one-half the total current. If, owing to a drop in speed or any 
other cause, the voltage of one generator drops, more load would be 
thrown on the other machine. As the tendency of a shunt gen¬ 
erator is to increase its voltage as the load decreases and decrease 
its voltage as the load increases, the machine that has been relieved 
of its load would tend to raise its voltage and would immediately 
take more load. Shunt generators are, therefore, well adapted to 
parallel operation, but they are not often used because of poor 
voltage regulation. 

Compound-Wound Generators in Parallel. A simple wiring 
diagram of two compound-wound generators connected in parallel 
is shown in Fig. 11. A is the armature; B is the series field; C is 



242 













MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 19 


the shunt field; D, E, and F are single-pole single-throw switches; 
G, H, and 1 are buses; and R is the shunt-field rheostat. The 
switches D and F connect the main leads from the machine ter¬ 
minals to the main buses G and I. The switches E connect a point 
between the armature and the series field on each machine to an 
equalizing bus H. 

Assume that No. 1 machine is in service and it is desired to 



place No. 2 machine in parallel with it. Bring No. 2 machine up 
to speed and adjust its voltage to about normal. Close switch F 
and switch E. This places the series field of No. 2 in parallel with 
that of No. 1 and the voltage of No. 2 will be increased. Now 
adjust the voltage of No. 2 by means of the field rheostat until the 
voltage of both machines is the same. Next close switch D. The 
load on No. 2 can now be adjusted by means of the field rheostat 
until the two machines are dividing the load properly. 

The voltage of the two machines can be compared in any one 


243 

































20 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


of several ways. A voltmeter may be connected to the buses per¬ 
manently and a second voltmeter arranged to be connected to any 
machine by means of plugs and receptacles, or a single voltmeter 
can be arranged to be plugged alternately to any two machines. 

On small generators the three single-pole switches are often 
replaced by a triple-pole switch. In this case the voltages of the 
running and the incoming machines are adjusted to equal value 
and the switch on the incoming machine is closed. The resulting 
sudden shift of load may not be objectionable in small machines. 

Before two machines can be paralleled, it must be determined 
whether the compounding is the same; that is, whether the rise in 
voltage from no load to full load is the same. A shunt resistance, 
Z, Fig. 11, is placed across the series field of each machine. By 
changing this resistance, the amount of current in the series field 
and thereby the amount of the compounding can be adjusted. 

When two machines are operating in parallel and one machine 
supplies more than its share of current, the resistance of the path 
through its series field coil should be increased. Since the resist¬ 
ance of the series field and its connection to the switchboard is low, 
putting a longer lead between the series field and the switchboard 
will usually give the desired result. 

Where very large generators are used, the cost of cables to 
the switchboard may be considerable. In such cases the usual 
practice is to place the equalizer bus under the machines and as 
close to them as possible. The equalizer switches are then placed 
on a base mounted on the frame of the machine, or on a pedestal 
mounted beside the machine. 

Direct-Current Generators in Series. The arrangement of di¬ 
rect-current generators in series is not very common in ordinary 
power work. Constant-current series-wound generators have some¬ 
times been connected in series for arc-light service. Probably the 
most common example of this practice has been the use of two 
shunt or compound-wound generators connected in series for Edi¬ 
son three-wire service. At present there are a large number of 
stations where shunt- or compound-wound machines are operated 
in series in order to obtain the high voltages now common in heavy 
traction service. 

No special connection is necessary in the machine itself to 


244 


MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 21 

connect it in series with another. The negative of one machine is 
simply connected to the positive of the next one, thus adding the 
voltages. 


Commutating=Pole Generators 

Characteristics. In addition to the fundamental types of 
direct-current generators already described, there is the comrnu- 



Fig. 12. Westinghouse Type Q Generator Showing Commutating Poles 

tating-pole type of generator. This differs from the above, in 
mechanical respect, only in the fact that midway between each 
pair of main poles there is a small pole. The electrical connec¬ 
tions differ from those of the non-commutating-pole machines only 
in the fact that the main current from the armature passes through 
the windings on the commutating poles, as well as, and in the 
same manner as, through the series fields already described for 
compound-wound generators. In the same manner the winding on 
the commutating poles may have a shunt across its terminals the 
same as the series field shunt £ shown in Fig. 9. The same remarks 
apply to commutating pole motors. 


245 



22 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


The object of the commutating poles is to prevent shifting 
of the non-sparking position of the brushes from no load to full 
load. This is accomplished, because the commutating pole produces 
the necessary flux for neutralizing the effect of armature reaction. 



Fig. 13. Wiring Diagram for Commutating Four-Pole Compound Generator 


Location of Brushes on Commutating-Pole Machines. Re¬ 
move one brush from a brush holder and in its place insert a fiber 
brush of the same dimensions as the brush removed. Through the 
fiber brush bore two holes, about the size of a lead in a pencil, at 
such a distance apart that the holes are over the centers of two 
adjacent commutator bars. Insert in these holes the leads from 


246 






































































MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 23 


two pencils so that the ends of the leads ride lightly on the com¬ 
mutator. To the other ends of the leads connect a low reading 
voltmeter or a millivoltmeter. The brushes should previously 
have been set in a line on the commutator passing through the 
center of the main pole piece. At no load excite the machine to 
give normal voltage and move the brush-holder yoke until the volt¬ 
meter connected to the exploring brush reads zero. This is the 
proper position for the brush and will be the same for full load, if 
the shunt around the commutating field has been properly adjusted. 

Fig. 12 shows a commutating-pole machine. Both motors and 
generators have the same arrangement of poles. Fig. 13 shows the 
electrical connection of a four-pole commutating-pole generator. 


SYNCHRONOUS CONVERTERS 

Comparison with D.C. Generator. In general appearance - 
and construction the synchronous converter resembles the direct- 
current generator. The chief difference in appearance is that the 
synchronous converter has a set of collector rings mounted on, 
and insulated from, the shaft usually on the opposite end from the 
commutator. Another difference is seen in the relative dimensions 
of the magnetic circuit, which is much smaller in the synchronous 
converter than in a direct-current generator of the same capacity. 
The commutator end of a synchronous converter, or rotary con¬ 
verter, as it is often called, is exactly like any direct-current 
generator. At the other end the collector rings are tapped to equi¬ 
distant points of the armature winding. As many taps are taken 
from the armature winding to each collector ring as there are 
pairs of poles. 

Uses. The rotary is commonly used for converting alternat¬ 
ing current into direct current. The voltage of the applied alter¬ 
nating current bears a fixed and definite ratio *to the value of the 
direct-current voltage on the commutator. However, the machine 
may be run as an inverted rotary, having direct current applied 
to the commutator and delivering alternating current at the 
collecting rings. 

Voltage Relations in Converters. Two-Ring Rotary. To un¬ 
derstand the voltage relations in converters, consider briefly the 


247 




24 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


case of a two-ring (single-phase) rotary. The maximum value of 
alternating-current voltage will occur when the commutator bars 
connected through the armature winding to the collector ring pass 
under the brushes. Assume E dc the value of direct-current volt¬ 
age. This is equal to the maximum value V of the alternating 
voltage. The effective value* V e is equal to the maximum value V 

V 

divided by y/2; that is V e equals ? since V equals Edc then 
V e equals E dc x 0.707 or V e . That* is, taking the voltage on the 
direct-current end of a single phase rotary to be 100 volts, the 

a.c. voltage across the rings nec¬ 
essary to give this must be 70.7. 

Three-Ring Rotary . Let the 
effective value V e for a single¬ 
phase rotary be represented by 
the diameter of a circle. Let 
Fig. 14 represent the relation 
of a.c. voltages in a three-ring 
three-phase rotary converter. 1 , 
2, and 3 represent the rotary 
rings where the impressed volt¬ 
age is applied. V 3 represents 
the value of voltage between 
any two rings. The following 
is a simple proof of the value of V 3 in terms of V e , and this in turn 
in terms of E dc . Since we have already shown 

Ve = — 

V2 



Fig. 14. relation of A. C. Voltages in a 
Three-Ring Three-Phase Rotary 
Converter 


Zi 

Cos 30° = -|- 

V o 

IT 


I. 

V e 


Cos 30° = i V 3 = 

Z V e 

* Alternating-current voltmeters read effective value of volts, not maximum 

value. 


248 







MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 25 


v.-YLv, 


E dc 

But Ve was shown to equal 


• *TT 3 ^dc O Tj 1 

. . y„ = - x — 7 = = .612 Edc 

° 2 V 2 

Which means that the alternating-current voltage across any two 


collector rings is equal to the 
direct-current voltage (meas¬ 
ured across brushes of opposite 
polarity) multiplied by 0.612. 
Conversely, the direct-current 
voltage is equal to the alternat¬ 
ing-current voltage across any 
two rings in a three-ring (three- 
phase) rotary converter divided 
by 0.612. 

Four-Ring Rotary. Consider 
next the case of a four-ring 
(two-phase) rotary, and as in 
the previous case, let 1> 2, 3, and 
4 represent the rings. In Fig. 15 



Fig. 15. Relation of A. C. Voltages in 
Four-Ring, Two-Phase Rotary 
Converter 


Cos 45° = 


_ V « 
~2V 4 

Cos 45° = ^2 = ^- 

V e 


But 


v = — 


Erie 

V 4 =^- = .500E„c 

V 2 


249 








26 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

Consider then the voltages on a fonr-ring (two-phase) rotary 
in which 1, 2, 3, and 4 are phases; the voltages between adjacent 
rings will be V 4 which equals .500 E dc , and the voltages across each 
phase will be the same as for a single-phase rotary, that is, 

F e = .707 E dc 

Six-Phase Rotary. Fig. 16 represents a six-phase relationship 
of voltages. The collector rings are numbered 1 , 2, 3, 4, 5 , 6. Con¬ 
sider the small triangle 1-2-a. 

Zi * 

Sin 30° = —pr— 

' 6 

Sin30° = iVT = ^ 

V 6 = iV e 

But V e = ^ 

V 2 

V 6 =4x^= = .354 E dc 
* V2 

Note that Fig. 16 shows single-phase, three-phase, and six- 

V 6 is the voltage between any 
two adjacent rings represented 
by the sides of a hexagon in¬ 
scribed in a circle whose diam¬ 
eter is equal to the effective 
voltage across the rings of a 
single-phase rotary. Measured 
in terms of the d. c. voltage, we 
have shown that V 6 equals 
E dc x .354. 

In the dotted triangle 1-3-5 
it will be noted the lines 1-3 , 
3-5 , or 5-1 represent the voltage 
between collector rings, that is 
F 3 . We have already shown 
that F 3 equals 2?d C x.612. 

A six-phase rotary has voltages impressed directly upon 
collector rings 1 and 4, 2 and 5, and 3 and 6, which, from Fig. 16, 


phase relationships of voltages. 



Fig. 16. Relation of A. C. Voltages in 
a Six-Phase Rotary Converter 


250 










MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 27 

will be seen to be equal to diameters of the circle. Therefore the 
same relation exists as for a single-phase rotary. Thus the 
alternating-current voltage across rings 1 and 4, 2 and 5, and 
3 and 6 is equal to d. c. voltage multiplied by .707. 

From the above explanation, and referring to Fig. 16, it will 
be seen that 

a. c. volts across 1 and 2-Ed C x .354 
a. c. volts across 1 and 3=Ed C x .612 
a. c. volts across 1 and J/- = E dc x .707 



Fig. 17. General Electric 600-Volt Compound-Wound Rotary Converter 


Conversely, Edc = F 6 between rings 1 and 2 -r .354 
Edc = V 3 between rings 1 and 3 -r .612 
Edc = V e between rings 1 and 4-^.707 
A modern type of railway rotary converter of the compound- 
wound type is shown in Fig. 17. 

Switching of Synchronous Converters. The following in¬ 
structions apply to the usual connections and to the switchboard 
equipment of General Electric compound-wound converters in 


251 




28 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


railway service. Referring to Figs. 18 and 19, a machine should 
be started as follows, it being assumed that all switches are open 
before starting and that the potential plug is inserted in the 
potential receptacle on the direct-current switchboard panel, thus 
connecting the machine to the voltmeter. (See note.) 



Fig. 18. Switching Diagram for Three-Phase Converters 
Courtesy of General Electric Company 

First: Close main high-tension switch A. 

Second: Close starting switch B upward. (For six-phase 
machines with tandem switches, both switches B and B B should 
be closed upward.) 

The machine will then run up to speed and lock in step, which 
will be indicated by a cessation of the beats of the direct-current 
voltmeter. 

Third: Close equalizer switch G. 


252 
























































































MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 29 


Fourth: Close field break-up and reversing switch E into the 
top position. 

Fifth: For three-phase machines throw starting switch B 
quickly from top to bottom contacts, Fig. 18. With six-phase 
machine, Fig. 19, throw starting switch BB quickly from top to 



Fig. 19. Connections of Starting Switches for Six-Phase Converters 
Courtesy of General Electric Company 


bottom contacts and then switch B from top to bottom contacts. 
Finally open switch B B. 

Note: If other machine or machines are carrying load when a com¬ 
pound-wound converter is started, the correct polarity may be insured by clos¬ 
ing the equalizer switch G when the machine locks in step. By watching the 
swings of the direct-current voltmeter as the machine approaches synchronism, 
switch G may be closed just previous to the last two or three swings, thus 
insuring proper locking on the first trial, if there is current for the series 
field from other machines. If the machine locks with the wrong polarity as 


253 



































































































30 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

indicated by the direct-current voltmeter needle going down off the scale, the 
field switch E must be closed first into the down position, which will cause 
the voltmeter to return above zero, when the switch E must be pulled out and 
closed into the top position. The reversal of polarity should be made while 
the machine is running on first starting tap. 

Sixth: Adjust direct-current voltage to approximately that 
of the busbars. 

Seventh: Push up the low voltage release of circuit breaker 
and close circuit breaker C. 

Eighth: Close main switch D. 

Ninth: Adjust the division of loads between machines, if 
more than one are in service, by means of field rheostats. 

Note: Machines as now built do not have a shunt to the series field, 
so that the series field shunt switch exists only on older machines. 

Shutting Down Synchronous Converter. To shut down a 
synchronous converter, open the circuit breaker C, pull out and 
turn the circuit-closing auxiliary switch to stop the ringing of the 
alarm bell; open the main switch D; open the high-tension alter¬ 
nating-current oil switch A; allow the machine to run down in 
speed until the voltage falls off to about one-fifth normal value 
before opening the field switch E or the starting switch B - open 
the field switch E, equalizer switch G, and starting switch B. 


THREE=WIRE SYSTEM 


Two Direct-Current Generators on Three-Wire System. In 

the ordinary three-wire system for incandescent lighting and 
+ power service, no particular 

precautions are required in 
starting or connecting the ma¬ 
chines; and either of the ar¬ 
rangements shown in Figs. 20 
and 21 may be adopted. The 
two sides of the system are 
almost independent of each 
other, and form practically separate circuits, for which the middle 
or neutral wire acts as a common conductor. There is, however, a 
tendency for the dynamos, Fig. 20, to be reversed in starting up, 
in shutting down, or in the case of a severe short circuit. This 


ife) "p v i 

l * 

> < 

L 

) c 

) 


|Q f 

< 

_ 

> < 

> ( 

> ( 

hi 


Fig. 20. Wiring Connections for Two 
D. C. Generators on Three-Wire 
System 


254 














MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 31 


can be avoided by exciting the field coils of all the dynamos from 
one side of the system, or from a separate source. To obtain good 
regulation, it is necessary to balance the load equally on both sides 
of the system. It is advisable to employ 220-volt motors on 110- 
volt 3-wire systems, and to connect them across the outside con¬ 
ductors so that the motor load shall not unbalance the system. 

Generators with Balancer Set. Fig. 21 represents a 220- 
volt generator connected to the outside wires of a three-wire 
system. Two 110-volt machines 
are connected in series across g-C“~"T 
the system, and the neutral con- 1 (o) I 
ductor connects with the inter- 
mediate point between them. If Fi s- 21. wiring Diagram for 220-voit 

^ Generator with Balancer Set on 

the system is perfectly bal- Three-Wire System 

anced, both 110-volt machines operate as motors without load. As 
the system becomes unbalanced, the machine on the heavier loaded 
side begins to operate as a generator and the other as a motor. 
The machines must be mechanically connected but can be sepa¬ 
rately regulated to give any desired voltage division between 
sides, and each machine can be compounded to compensate for 
unequal line losses and neutral drop when the system is unbalanced. 



TRANSFORMER 



Fig 22 Wiring Diagram for Three-Wire System with Rotary Converter Showing 
Transformer Connections 


Three-Wire Systems from Rotary Converters. Where rotary 
converters are used to supply a three-wire system, the neutral 
conductor can be connected either to the middle points of the 


• 255 




































32 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

transformer secondaries, or to a compensator connected to the 
alternating-current leads. 

The arrangement of the transformers or compensator windings 
must be such that they cannot operate reactively to prevent the 
current flow necessary to maintain the neutral, Fig. 22. Three- 
wire generators are often used for supplying three-wire systems. 
This machine is like a two-wire generator but has the armature 
winding tapped at suitable points. These taps are connected to a 


Fig. 23. Crocker-Wheeler 75 Kw. Three-Wire Generator 

compensator or a balance coil from the middle point of which 
the neutral is obtained. Several forms of this type have been 
used by various manufacturers. One of these has the armature 
taps brought out to collector rings. The compensator is then 
mounted separately from the machine and connected through 
brushes to the rings. 

Since this form requires renewals and attendance on two or 
more sets of brushes and rings, some manufacturers have provided 


256 ' 




MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 33 

a winding in the armature to generate the voltage supplying the 
neutral conductor, which thus requires but one set of brushes and 
one collector ring, Fig. 23, in addition to the commutator brushes. 

A later type of machine has a revolving compensator. This 
consists of a circular magnetic core upon which are mounted the 
coils. The core and coils are bolted directly to the back end of the 
armature spider. The single neutral connection is carried through 
the spider to a single collector ring mounted on the outer end of 
the commutator shell. This form has the advantages of few 
collector rings and brushes, small space, and greater simplicity in 
wiring. 


DIRECT=CURRENT CONSTANT=POTENTIAL MOTORS 

Shunt-Wound Motors. A motor to operate at nearly con¬ 
stant speed, with varying loads, on a d.c. constant-potential 
system (110- or 220-volt lighting circuits) is usually plain shunt- 
wound. This is the commonest form of stationary motor. The 
field coils are wound with wire of such a size as to have the proper 
resistance and resulting magnetizing current; and since the poten¬ 
tial applied is practically constant, the field strength is constant. 

Starting. In starting shunt motors, no trouble is likely to 
occur in connecting the field to the circuit. The difficulty is with 
the armature current, because the resistance of the armature is 
very low in order to get high efficiency and constancy of speed, 
and the rush of current through it in starting might be twenty or 
more times the normal number of amperes. To avoid this exces¬ 
sive current, motors are started on constant-potential circuits 
through a rheostat or starting box containing resistance coils. 

The main wires are connected through a branch cut-out (with 
safety fuses), and preferably also a double-pole knife switch Q, 
to the motor and box, as indicated in Fig. 24. When the switch 
Q is closed, the arm S being in its left-hand position, the field 
circuit is closed through the contact stud f, and the armature cir¬ 
cuit is closed through the resistance coils aaa which prevent the 
rush of current referred to. The motor then starts and, as the 
speed rises, it generates a counter e.m. f., so that the arm S can 
be turned as shown until all 4he resistance coils aaa are cut out. 


257 


34 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


The arm 8 should positively close the field circuit first, so that the 
magnetism reaches its full strength (which may take several sec¬ 
onds) before the armature is connected. 

In the arrangement shown in Fig. 24, the release magnet has 
its coils in series with the field. As long as the motor is in opera¬ 
tion, the core is energized and the arm S is held in the position 
shown. If, however, the current applied to the motor is cut off 
and the motor comes to rest, the core of the magnet loses its attrac- 



Fig. 24. Wiring Diagram for Connections of Shunt-Wound Motor to Starting Box 


tive force, and the arm 8 is released, being automatically moved 
back to the starting position by a spring. 

The coils aaa are made of comparatively fine wire which 
can carry the current only for a few seconds in a starting box j 
but if the wire is large enough to carry the full current continu¬ 
ously, it is called a “regulator”, because the arm S may be left so 
that some of the resistances aaa remain in circuit, and they will 
have the effect of reducing the speed of the motor, which is often 
very desirable. 


258 



















































MANAGEMENT OP DYNAMO-ELECTRIC MACHINERY 35 

In some cases where a circuit is used exclusively for a single 
motor, the speed is regulated without heavy resistances by varying 
the e. m. f. of the dynamo which supplies the circuit. The dynamo 
regulator is then placed near the motor. The advantage is that 
the regulator is not compelled to control a heavy current, but a 
special circuit of unvaried pressure must be provided to keep the 
field of the motor constant. 

Speed Control. The speed c'ontrol of a shunt motor may be 
simply obtained as follows: 



Fig. 25. Fort Wayne Northern Type B Shunt-Wound Motor 


(a) For lower speeds, insert resistance in series with the 
armature circuit. The resulting internal resistance drop reduces 
the value of the voltage applied to the armature terminals, and 
thus reduces the speed. 

(b) For higher speeds, insert resistance in the shunt-field 
circuit. This reduces the magnetic flux and, to generate the same 
counter e. m. f., the motor must speed up. 

The field circuit of a shunt motor should never be opened 
while pressure is still applied to the armature terminals, as under 
these conditions the armature current becomes very excessive and 
the armature is likely to race and be damaged. A moderate 


259 




36 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


decrease in field strength only is allowable; otherwise sparking 
becomes excessive. Fig. 25 shows a Fort Wayne Northern Type B 
shunt-wound motor. 

Series-Wound Motors. The ordinary electric railway motor 
on the 600-volt system is the chief example of the class, Fig. 26. 
Motors for fans, pumps, or electric elevators and hoists are either 
of this kind or of the compound type. A rush of current tends to 
occur, when the series type of motor is started, similar to that in 
the case just described; but it is lesfc, because the field coils are in 
series, so that their resistance and self-induction reduce the excess. 



I ig. 20. Box Frame Railway Motor 
Courtesy of General Electric Company 


Furthermore, the counter e.m.f. is greater even at low speed 
because the heavy current produces a strong field. 

The connections, as indicated in Fig. 27, are very simple, the 
armature, field-coils, and rheostat all being in series and carrying 
the same current. 

The series-wound motor on a constant-potential circuit does 
not have a constant field strength, and does not tend to run at 
constant speed, like a shunt motor. In fact it may “race” and 
tear itself apart if the load is taken off entirely; it is, therefore, 
suited only to railway, pump, fan, or other work where variable 
speed is desired, and where there is no danger of the load being 
removed or a belt slipping off. It is also used where the potential 
is subject to sudden and large drops, as on the ends of long trolley 


260 




MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 37 

circuits, because in such a case a shunt motor becomes momentarily 
a generator and sparks very badly. The fields of series motors 
are sometimes ‘ ‘ overwound, ? ’ that is, so wound that they will have 
their full strength with even one-half or one-third of the normal 



Fig. 27. Wiring Diagram for Series-Wound Motor Connections 


current. The objects are: to secure a nearly constant speed with 
varying loads; to enable the motor to run at high efficiency when 
drawing small currents; and to prevent sparking at heavy loads. 

In multipolar motors having more than two field-coils, the 
coils are all connected together, and are equivalent to the single 



Fig. 28. Wiring Diagram for Four-Pole Sh,unt and Series-Wound Motors 


pairs of coils shown in the several diagrams. Being separated, 
however, it is sometimes necessary to trace out the connections. 
Fig. 28 represents the necessary connections for a four-pole motor, 
shunt-wound and series-wound. 


261 























38 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

Differentially-Wound Motors. This is a shunt-wound motor 
with the addition of a coil of large wire on the field, connected 
in series with the armature in such a way as to oppose the magnet¬ 
izing effect of the shunt winding and weaken the field, thus caus¬ 
ing the motor to speed up when the load is increased, as an offset 
to the slowing-down effect of load. 

It was formerly used for obtaining very constant speed, but 
it has been found that a plain shunt motor is sufficiently constant 
for almost all cases. The differential motor, if overloaded, has the 
great disadvantage that the current in the opposing (series) field- 



Fig. 29. Wiring Diagram for Compound-Wound Motor Connections 


coil becomes so great as to kill the field magnetism; and instead of 
increasing or keeping up its speed, the armature slows down or 
stops and is likely to burn out; whereas a plain shunt motor can 
increase its power greatly for a minute or so when overloaded, 
and will probably throw off the belt or carry the load until the 
latter decreases to the normal amount. 

Compound-Wound Motors. This type of motor is also pro¬ 
vided with both shunt- and series-field windings, Fig. 29, but in 
this instance they magnetize the field in the same direction, or, in 
other words, their effect is cumulative. This type of motor pos¬ 
sesses the powerful starting toyque feature of the series motor, 
but a less variable speed with varying loads. It is employed where 


262 




















MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 39 

a great starting torque and a fairly uniform running speed are 
required, as, for example, with electric hoists or elevators. 

Method of Reversing Direction of Rotation in Motors. To 
reverse the direction of any direct-current motor, the direction of 
the current in either the field or the armature must be reversed. 
The direction of rotation would not be changed if the current in 
both the field and the armature were reversed. If the motor is 



Fig. 30. Frame and Field Coils of Commutating-Pole Motor 
Courtesy of Crocker-Wheeler Company 

compound or differentially wound and the direction of rotation 
is to be reversed, the crurrent in the series winding must be kept 
so that it either assists or opposes, as the case may be, the current 
in the shunt field, whether the rotation is reversed by changing 
the current through the armature or the shunt field. 

Commutating-Pole Motors. .The general remarks as to me¬ 
chanical and electrical points of difference between commutating- 


263 









40 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


SWITCH 



MOTOR CONNECTED EOF COUNTER CLOCKWISE RO 777 TJON 

F'ic 31. Wiring Diagram of Rotation Connections for Commutating Four-Pole 

Shunt Motors 


SWITCH 



MOTOR CONNECTED FOR COUNTER CLOCKW/SE ROTATION 


Fig. 32. Wiring Diagram of Connections for Commutating-Pole Bipolar Compound 

Motors 


264 . 
















































































































































MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 41 

and non-commutating-pole types of generators apply to similar 
types of motors. 

The electrical neutral on commutating-pole motors is deter¬ 
mined by shifting the brushes until the same speed is obtained in 
both directions with the same value of field current and the same 
voltage on the d. c. mains. 

Fig. 30 represents the frame and field coils of a standard 
commutating-pole motor, and Figs. 31 and 32 show the method of 
wiring commutating-pole motors for both the four-pole shunt 
type and two-pole compound type. 


ALTERNATING=CURRENT GENERATORS 


The present-day alternator consists of a stationary armature, 
called the stator, wound to generate either single or polyphase 
electromotive force, and a revolving field, called the rotor, excited 
from a separate 125- or 250-volt source. The exciting current is 


Fig. 33. Westinghouse Type E, 75 K. V. A. Generator, Showing Collector End 


265 


42 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

brought to the revolving field through collector rings mounted on 
and insulated from the shaft, the ends of the field winding being 
connected to these rings. Fig. 33 shows such a machine designed 



Fig. 34. Three-Phase Crocker-Wheeler Alternator, Showing Separate D.C. Exciter 
on the Same Shaft 

for direct connection to its prime mover. Machines of this class 
are quite often built with a small direct-current exciting generator 
mounted on the same shaft, as shown in Fig. 34. Small alternators 



Fig. 35. Voltage Curves for Two-Phase Alternator 


sometimes have revolving armatures, the current, single or poly¬ 
phase, being taken from collector rings connected .to the armature 
windings. 


266 















MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 43 

Single-Phase Type. There are a number of plants in this 
country still operating single-phase systems, bqt the advantages of 
using polyphase motors rather than single-phase motors in most 
power installations has caused this system to be practically aban¬ 
doned. The single-phase generator need not be considered in dis¬ 
cussing modern practice, since it is so little used. 



Mg. 36. Wiring Diagram for Two-Phase Four-Wire Generator with Armature 
Windings Ninety Degrees Apart 


Two-Phase Type. A two-phase alternator has two armature 
windings arranged so that their voltages are 90 degrees out of 
phase. Fig. 35 shows the two voltage waves plotted in their rela¬ 
tions, one being one-fourth of a cycle ahead of the other. Fig. 
36 shows a two-phase four-wire generator with the armature wind- 



Mg. 37. Wiring Diagram for Two-Phase Generator Arranged for Three-Wire System 

ings represented 90 degrees apart. The voltages on phase A. and 
phase B are equal. 

Two-phase generators are sometimes arranged with their two 
sets of armature windings connected together, as shown in Fig. 
37. In this case only three wires are carried out to the distribut¬ 
ing system. If the voltage of either phase is equal to E, then the 


267 




















44 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


voltage across the free ends of the inter-connected phase will be 
equal to ExVH. (See Fig. 37.) 


Cos 45° = ^ 


Cos 45° = i V3 

z 


J-V2 


\En 

E 


E r = E x V2 

The current in any wire of a two-phase four-wire system is 

KW 
L ~ 2 E 

in which KW is capacity of generator; E is voltage of phase 


A or B. 



Fig. 38. Voltage Curves for Three-Phase Generator 

Three-Phase Type. Three-phase generators have their arma¬ 
ture windings divided into three sets of coils so arranged as to pro¬ 
duce electromotive forces 120 degrees apart, Fig. 38. Armatures 
may be either Y- or A -connected, Figs. 39 and 40. In a Y-con- 
nected system, the line voltage is the phase voltage multiplied by 
V 3 as shown, thus: 

iE a 


Cos 30° = 


E 


Cos 30° = JV3 


* V3= ii 


E r = E\/ 3 


the line current is found to be the same as the current per phase. 
In a A-connected system, the line voltage is the same as the 


268 






MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 45 

phase voltage, but the current per line is the \/3 times the cur¬ 
rent per phase. In either system 

w -Ei y 3" 

for noninductive circuit, in which W is watts output; E is pres¬ 
sure in volts, and 1 is current in amperes. 

For an inductive circuit whose power factor is less than unity, 

W = .E7y3'COS</> 

in which cos <£ is power factor. 



Fig. 39. Wiring Diagram for Y-Connected Three-Phase Generator 


Alternators in Parallel. To run two alternators in parallel, 
several conditions have to be fulfilled: The incoming machine— 
as in the case of direct-current machines—must be brought up to 



Fig. 40. Wiring Diagram for A-Connected Three-Phase Generator 


nearly the same voltage as the first one; it must operate at exactly 
the same frequency; and, at the moment of switching in parallel, 
it must be in phase with the first machine. This correspondence 
of frequency and phase is called ‘‘synchronism. 


269 

























46 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


Synchronizing Alternators by Lamp Indicator. It is impos¬ 
sible with mechanical speed-measuring instruments to determine 
the speed as accurately as is necessary for this purpose. There is, 
however, a very simple method of electrically determining small 
differences in speed or frequency. In Fig. 41, let M and N repre¬ 
sent two single-phase alternators, which can be connected by 
means of the single-pole switch A B. Across the terminals of the 
switch is connected an incandescent lamp L, capable of standing 

twice the voltage of either ma- 

_, chine. When IB is open, the 

circuit between the machines is 
completed through L. The two 
machines may be connected in 
parallel as follows: Assume ma¬ 
chine M already in operation; 
bring up machine N to approximately the proper speed and volt¬ 
age; then watch lamp L. If machine N is running a very little 
slower or faster than machine M, the lamp L will glow for one 



Fig. 41. Diagram of Two Single-Phase 
Alternators Arranged in Parallel 



Fig. 42. Diagram of Connections for Synchronizing High-Voltage Alternators 
Through Step-Down Transformers 


moment and be dark the next. At the instant when the volt¬ 
ages are equal in pressure and phase, L will remain dark; but 
when the phases are displaced by half a period, the lamp will 
glow at its maximum brilliancy. Since the flickering of the 


270 






































MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 47 

lamp is dependent upon the difference in frequency, the machines 
should not be thrown in parallel while this flickering exists. The 
prime mover of the incoming machine must be brought to the 
proper speed; and the nearer machine N approaches synchronism, 
the slower the flickering. When it is very slow, and at the instant 
when the lamp is dark, throw the machine in parallel by closing the 
switch across A B. The machines are then in phase, and tend to 
remain so, since if one slows down, the other will drive it as a 
motor. It is better to close the switch when the machines are 
approaching synchronism rather than when they are receding from 
it; that is, at the instant the lamp becomes dark. 

Fig. 42 shows the method of synchronizing high-voltage alter¬ 
nators through step-down transformers. When two three-phase 
alternators are first placed in operation, synchronizing connections 
should be made across each phase. If all the lamps become bright 
or dark simultaneously, the alternators are ready for parallel 
operation. After all phases have once been tested, it is only neces¬ 
sary to compare a corresponding phase from each machine to 
indicate synchronism. 

The connections, as shown 
in Fig. 42, indicate synchro¬ 
nism when the lamps are 
dark. If it is desired that a 
condition of synchronism shall 
be indicated when the lights 
are at maximum brightness, 
reverse the secondary connec¬ 
tion of either one of the poten¬ 
tial transformers. 

Synchronizing Alternators 
by Synchronizer. Synchro¬ 
nizing by means of lamps is not 
considered accurate enough 
in the modern station. There 
is manufactured an instru¬ 
ment called a “synchronizer,” or “synchronism indicator,” which 
gives much more accurate results. One form of this instrument 
shown in Fig. 43, has a revolving pointer which indicates, by its 



271 


48 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

position, the exact point of synchronism; and by its direction of 
rotation, whether the incoming machine is running too slow or 
too fast. Lamps are usually provided with this instrument as a 
check on its operation and for use in case of a failure of the instru¬ 
ment due to a burn-out or other cause. In the type shown, the 
lamp is back of the scale and lights up only when the machines 
are at or near synchronism. 



Fig. 44. Wiring Diagram for Synchronism Indicator with Potential Transformers, 
Secondaries Grounded. Synchronism Is Indicated When the Lamps Are Dark 


Figs. 44 and 45 show two methods of connecting a synchronizer 
to two machines (one running and one starting) by means of plugs 
and receptacles mounted on the switchboard. Where the secon¬ 
daries of the potential transformers can be grounded, which is 
usually the case, a common ground return can be used and the 
connections are much simplified. 

When two alternating-current machines have been connected 


272 


























MANAGEMENT OP DYNAMO-ELECTRIC MACHINERY 49 


in parallel, the division of load should be adjusted. This cannot 
he accomplished as in direct-current machines by adjustment of 
the field rheostat. Change in field strength will cause more current 
to flow, hut it will he 90 degrees out of phase with the potential 
and will not represent actual power. The only way to make the 
two machines supply proportional amounts of power is to adjust 
the input to their respective prime movers. The governor of the 



prime mover should be adjusted as if for an increase in speed to 
make the machine carry more load, and conversely to make the 
machine carry less load. 

If it is found necessary to increase the voltage of machines 
operating in parallel, the rheostats of all machines should be 
adjusted proportionally. If the rheostat of only one machine is 
shifted, cross currents will he caused to flow between machines, 


273 

































50 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

which do not represent actual power but do cause undesirable 
heating of the machines. 

ALTERNATING=CURRENT MOTORS 

Alternating-current motors may be generally classed as induc¬ 
tion and synchronous types. The induction type of motor is par¬ 
ticularly rugged in design, is simple of operation, requires little 
attention and a minimum of accessories; it does not tend to disturb 
the wave form of the system on which it is operating, and with 
normal load its power factor is fixed. 

The synchronous motor closely resembles the revolving-field 
type of alternator and, in general, any standard type of alternator 
may be operated as a synchronous motor. This type of motor, 
therefore, requires practically the same number of accessories as an 
alternator. It requires care and skill on the part of the operator 
both in starting and in making the adjustments necessary for. 
proper operation on the system. Since it is a synchronous piece of 
apparatus, like the generators supplying current to it, it may 
cause disturbance on the system on w T hich it is operating unless 
very carefully handled. The power faqtor of this type of motor 
may be controlled by varying the excitation of its field. This 
feature allows the synchronous motor to be used for correcting 
the power factor of a system and causes its use in a large number 
of cases where the induction motor would otherwise be used be¬ 
cause of its greater simplicity and ease of operation. 

Induction Motors 

Squirrel-Cage Type. The simplest form of polyphase induc¬ 
tion motor is the “squirrel-cage” type, so-called because the rotat¬ 
ing element with its windings short-circuited by a heavy copper 
end ring resembles a squirrel cage. Fig. 46 shows the rotor from 
a machine of this type. This rotor, also known as the secondary 
or armature, is made up of thin punched discs of specially treated 
iron. These punchings are provided with slots in which the 
windings are placed. 

The stator, called also the field or primary, has windings 
distributed in the same manner as the winding in an alternator 
armature. The ends of the windings are brought out to a terminal 


274 


MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 51 

board mounted on the frame of the motor, and the service lines are 
connected to the motor terminals. No connection is made to the 
rotor from any external source. Fig. 47 shows an exploded view of 
a motor of the type described. 

The polyphase currents in the stator windings produce a 
revolving magnetic field. This in turn induces currents in the 
short-circuited winding on the rotor, which, on account of the 
reaction with the revolving magnetic field, causes the rotor to 
revolve. In order for any current to be induced in the windings 
of the rotor there must be a difference in speed between the revolv¬ 
ing magnetic field and the rotor. It therefore follows that an 



Fig. 46. Showing End Construction of Squirrel-Cage Kotor 
Courtesy of General Electric Company 


induction-motor rotor never can revolve at exactly the same speed 
as the magnetic field of the stator; that is to say, it cannot attain 
synchronous speed. The difference between'the speed of the rotor 
and the revolving magnetic field is called the “slip” of the motor. 
In motors of this class the slip varies from 2 to 6 per cent, depend¬ 
ing on the size of the motor, large motors having the lower per¬ 
centage of slip. Motors of the squirrel-cage type take a current 
equal to 3 to 4$ times normal full-load running current to produce 
full-load starting torque. The normal full-load efficiency of two- 
or three-phase motors of this type varies approximately from 87 


275 














52 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

to 93 per cent, depending on the size of the motor. The power 
factor at full load varies from 85 to 90J per cent. Motors of this 
type operate at constant speed. Variable-speed a. c. motors will be 
considered later. 

Reversing. To reverse the direction of rotation of induction 
motors, interchange leads as follows: For a two-phase four-wire 
motor, interchange the two leads of one phase; for a two-phase 
three-wire motor, interchange the two outside leads; for a three- 
phase motor, direction of rotation can be reversed by interchanging 
any two of the motor leads. 



Fig. 47. Exploded View of Crocker-Wheeler Induction Motor 


Output. The output of an induction motor varies with the 
square of the voltage at the motor terminals. If, for instance, 
the terminal voltage happens to be 15 per cent low (85 per cent 
of the rated voltage), a motor, which at the rated voltage gives a 
maximum of 200 per cent of its rated output, will give only 
(85/100) 2 x 200, or 144 per cent of its rated output. 

When an induction motor is overloaded, it draws an excessive 
current from the supply mains. The torque increases up to a 
certain value of slip. The rotor at this time has dropped back in 


276 






MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 53 


position to such a point that the machine is unstable and, if the 
load is increased beyond this value, the machine comes to rest. 
This is called the “pull out” point of the motor. The speed of an 
induction motor varies directly with the frequency of the circuit on 
which it is operating. 

Starting Compensator. It has already been pointed out that 
an induction motor of the squirrel-cage type can be started by 
simply closing the stator, or primary switch, but this calls for a 
very large rush of current. In order to cut down the starting 



Fie 48 Type NR General Electric Starting Compensator with No-Voltage and 
Overload Release with Enclosing Cover 


current, when the maximum starting effort is not necessary, a 
starting compensator is usually employed. This compensator is an 
autotransformer, reducing the potential at the terminals of the 
motor and consequently diminishing the current taken by it. 

Fig 48 illustrates a compensator manufactured by the General 
Electric" Company, and Figs. 49, 50, and 51 show the connections 
employed for two- and three-phase motors with compensators, b ig. 
48 shows a compensator with overload relays mounted above it. 
These relays are arranged to trip the oil switch, when the cur- 


277 













54 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


rent is excessive, and have time limit dashpots so that the switch 
will not trip during the starting operation. Fuses are sometimes 
used instead of these overload relays. 

This type of compensator consists of coils (three for three- 
phase, two for two-phase) wound upon laminated iron cores, a 
spring return double-throw oil switch assembled in a metallic case, 
and a no-voltage release. To start the motor the switch should be 
thrown into the starting position with a quick firm thrust and held 
there until the motor comes up to speed (which usually requires 
but a few seconds) and then, with one quick firm movement, it 
should be pulled over into the running position, where it is held by 
a lever engaging with the no-voltage release mechanism. 



Fig. 49. Wiring Diagram for Three-Phase Starting-Compensator with Overload 

Release 

Courtesy of General Electric Company 

Never, in any case, should the motor be started by “ touch¬ 
ing,’ ’ that is, by throwing the switch partly into the starting posi¬ 
tion and pulling it quickly out a number of times. This does not 
reduce the rush of current at starting, but, on the contrary, it 
produces a number of successive rushes in place of the one which 
it has attempted to avoid and, what is often a more serious matter, 
causes the contact fingers to be so badly burned that it is necessary 
to replace them. 

When, however, the switch is properly thrown into the starting 
position, the current passes through the compensator. The wind¬ 
ings of the compensator should be provided with a number of 
taps, so that the motor current may be obtained at a voltage com 


278 




















































MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 55 


siderably less than the line potential and thus start the motor with 
a minimum disturbance on the line. 

With the switch in the running position, the compensator 



Fig. 50. Wiring Diagram for Two-Phase Starting Compensator for Four-Wire 

Circuit with Fuses 

Courtesy of General Electric Company 

windings are entirely disconnected and the motor takes its current 
directly from the lines at full potential. 

Compensators are usually connected for low starting voltage 



Fig. 51. Wiring Diagram for Two-Phase Starting Compensator for Three-Wire 

Circuit 

Courtesy of General Electric Company 

and torque. If the motor will not start its load with these con¬ 
nections, the next higher voltage taps should be tried, and so on 
until taps are found which will give the required torque. Motors 


279 




















































































































56 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

of small size (say, five h.p. or under) are usually started by com 
necting directly to the line without resistance or compensator. 

Polar-Wound Type. Another form of constant-speed induc¬ 
tion motor is one in which the rotor is definite or polar wound. 



Fig. 52. Diagram of Simple Controller for Regulating the Resistance in the Rotor 
of a Slip-Ring Motor 

The ends of this winding are connected to a resistance inside 
the rotor, arranged to be cut out while the machine is running, 
by a sliding contact, operated by a device on the motor shaft. 


280 















































MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 57 

Starting. This type of motor is started without the use of a 
compensator in the leads to the stator to reduce the applied voltage. 
The device for cutting out the resistance is set so that all the re¬ 
sistance is connected in the rotor circuit when the motor is at rest. 
The stator, or primary circuit, is connected directly to the line and, 
as the motor attains speed, the successive steps of resistance are 
cut out until, on the last step, the resistance is short-circuited. The 
resistance must not be left in circuit after the motor has attained 
normal speed, since it is not intended for regulating the speed 



Fig. 53. . Control Diagram for Slip-Ring Induction Motor 


of the motor. This motor comes up to speed in about 15 to 18 
seconds. 

Motors of this type exert a high starting torque. For instance, 
with a starting current 1^ times full-load current, 1^ times normal 
full-load torque is obtained. The power factor and efficiency of 
these motors are about the same as for the squirrel-cage type. 

Slip-Ring Type. Still a third type of polyphase motor is 
one which has the polar-wound rotor similar to the one previously 
described. However, the ends of the Y-connected rotor windings 
are brought out to three collector rings mounted on and insulated 


281 



































































58 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


from the shaft. Brushes bear on these rings and connect to some 
form of Y-connected resistance. 

Control. In most sizes of motor a controller, similar to the 
ordinary street-car controller, cuts out the resistance in the rotor 
circuit step by step, the resistance being entirely short-circuited 


forward 

/ 2 3456 7391011 

II 


Backward 

//H>9 37fS43£t 



Connections for 
Three Hf/re System 


Connections of Doubfe Broke Coi/s when used 
|_p Connect Sing/e .Coi/ in some manner 


Fig. 54. Wiring Diagram for Control Mechanism of Slip-Ring Induction Motor 


on the final step. The current to the stator or primary of the 
motor may also pass through the controller. Especially is this the 
case if the motor is to be operated in either direction. Figs. 52, 53, 
and 54 each show a method of control for the slip-ring type of 
induction motor. 


282 






































































MANAGEMENT OE DYNAMO-ELECTRIC MACHINERY 59 

In larger sizes of motor, the control is accomplished by a 
system of electrically-operated contactors which give the same 
sequence of connections as the manual control already shown. 
This type of motor may be operated at constant speed after all 
resistance is cut out of circuit, or it may be used as a variable- 
speed motor, in which case the resistance must be proportioned 
for continuous duty on any point of the control. Examples of 
this kind are elevators, cranes, hoists, and other applications re¬ 
quiring variable speed. 



Fig. 55. Type KS Single-Phase Induction Motor 
Courtesy of General Electric Company 


Starting torque and current in this type of motor depend upon 
the resistance in the secondary circuit, full-load current giving 
approximately full-load torque. 

SingIe=Phase Motors 

Split-Phase Type. Owing to its simplicity, strength, and 
good electrical characteristics, the squirrel-cage polyphase motor is 
generally recognized as the ideal type for use on alternating-cur¬ 
rent power circuits. There are, however, many localities where 
for various reasons it becomes necessary for the central station to 
supply single-phase current to power consumers. The single-phase 
motor in sizes from about 1 to 15 h.p. takes care of such conditions. 


283 






60 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

Fig. 55 shows a General Electric single-phase motor, while 
Fig. 56 shows a Century Electric single-phase motor. This type of 
motor is suitable for constant-speed service where torque at starting 
does not exceed 140 per cent of full-load value. 



Fig. 56. Exploded View of Century Electric Split-Phase Induction Motor 


Starting. In starting, the rotor revolves freely on the 
sliaft until approximately 75 per cent of the normal speed is 


INTERNAL CONNECTION 


EXTERNAL CONNECTIONS 





LINE 


S TART INC 
3 OX 


Q 

m 




°> 


( 3=3 


|y 


MOTOR. 


>a 


Fig. 57. Connections of Single-Phase Induction Motor with No-Voltage Release 

Starting Box 


reached; the load is then picked up by the automatic action of a 
centrifugal clutch. The motor is started by means of a starting box 
containing resistance and reactance. 


284 











































MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 61 


An induction motor designed to run on polyphase circuits 
will not start when its stator is connected directly to a single¬ 
phase circuit but, by providing the stator with a polyphase 
winding and ‘ ‘ splitting the phase ’ ’ of the applied single-phase cur¬ 
rent, sufficient starting torque is obtained. The current passing 
through the starting device will lag in the circuit having the 
reactance and cause the magnetic field to revolve. As soon as the 
motor has come up to speed, the connections to the stator are 
switched so that it is connected directly to the single-phase circuit. 
The motor will then continue to operate as a single-phase motor. 
Fig. 57 shows the connections necessary to operate the motor shown 
in Fig. 55. If a single-phase motor is started up by any external 
means and then thrown on the single-phase mains, it will continue 
to operate as a single-phase motor. 

The efficiency of this type of motor at normal load varies from 
70 per cent to 84 per cent, and the power factor from 67 per cent 
to 87 per cent in sizes of motors from 1 to 15 h.p. 

Reversing. To reverse the direction of rotation, interchange 
any two of the three leads to the motor terminal block. 

Repulsion Induction Motor. Another type of single-phase 
motor is that known as the “repulsion induction motor”. The 
leading characteristics of the direct-current series-wound motor 
are well known. Operating through a wide range of speed and 
torque, this type has, however, no inherent speed regulation and its 
use is consequently confined either to fixed loads, like fans or pres¬ 
sure blowers, or to varying loads where the motor-controlling device 
is constantly under the operator’s guidance. The speed, torque, 
and load characteristics of the series-commutator-type alternating- 
current motor being distinctly analogous to that of its direct-cur¬ 
rent prototype, the design fails to meet the requirements of con¬ 
stant-speed power service, this service demanding a motor which 
maintains good regulation after having once been bi ought up to 
speed, with torque values increasing as speed decreases; in other 
words, characteristics approaching those of the direct-current com¬ 
pound motor having the usual proportion of series-field winding. 

The repulsion induction motor, however, gives this combina¬ 
tion of series and shunt characteristics; that is, a limited speed 
and an increased torque with decrease in speed. In the stiaight 


285 



62 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


repulsion motor, to secure the necessary starting torque, a direct- 
current armature is placed in a magnetic field excited by an alter¬ 
nating current and short-circuited through brushes set with a pre¬ 



determined angular relation to the stator. To further improve the 
operating characteristics of the plain repulsion motor, a second set 
of brushes (i.e., the compensating brushes) is placed at 90 elec- 


286 




































MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY G3 

trical degrees from the main short-circuiting brushes (i. e., the 
energy brushes), Fig. 58. The compensating field is auxiliary to 


Fig. 60. Westinghouse Type AR Single-Phase Repulsion Motor 

the main field and impresses upon the armature an electromotive 
force in angular and time phase with the electromotive force gen- 


Fig. 59. 


Type RI Siugle-Phase Repulsion Induction Motor 
Courtesy of General Electric Company 


287 





Fig. 61. Induction Motor Driving Two Beaters Through Silent Chain 
Courtesy of Ceneral Electric Company 

speed, possessing heavy starting torque and high, power factor at 
all loads as well as excellent efficiency constants. The motor has no 
tendency to spark or flash over, since the armature coils, succes¬ 
sively short-circuited by the energy brushes, are not inductively 
placed in the magnetic field and have consequently only to com¬ 
mutate a low generated voltage. Figs. 59 and 60 show standard 
types of repulsion induction motors. 

Starting Torque and Current. Starting torque is 200 or 250 
per cent of rated-load torque with rated-line voltage. A starting 
current of 225 per cent of rated-load current is required to produce 


64 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

erated by the main field. In addition to correcting phase relation 
between the current and the voltage, thus giving approximately 
unity power factor at full load and power factors closely approach¬ 
ing unity over a wide range of load, the compensating field serves 
to restrict the maximum no-load speed and also permits, where 
varying speed service is involved, slight increase over synchronous 
values. The compensated repulsion motor is practically an induc¬ 
tion motor capable of operation either above or below synchronous 


288 











MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 65 

rated-load torque. Where it is desired to reduce the starting cur¬ 
rent to the minimum, starting rheostats may be used. 

The efficiency of the repulsion induction motor varies from 
67 to 85 per cent and the power factor from 94 to 99 per cent, 
depending on the size of the motor. 

The motor may be constant speed, constant speed reversible, 
variable speed, or variable speed reversible. 

Typical Induction-Motor Installations. Induction motors of 
the three kinds described are extensively used in all manner of 
i 



Fig. 62. Induction Motor Belted to Berlin Sander 
Courtesy of Westinghouse Electric and Manufacturing Company 

industrial plants, the type of motor depending upon its applicabil¬ 
ity to the work at hand. Figs. 61 and 62 show induction motors in 
different industrial applications. 

Synchronous Motors 

As previously stated, the synchronous motor resembles the 
revolving-field generator, except that the field of the synchronous 
motor may be provided with a squirrel-cage winding. Fig. 63 
shows a Westinghouse synchronous motor connected as a synchro¬ 
nous condenser. 

Starting. This winding enables the synchronous motor to 
start up as an induction motor. Some device, such as a compen- 


289 


















66 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


sator, is used to reduce the line voltage, applied to the stator or 
primary of the motor, so as to reduce the rush of current in start¬ 
ing. Since the synchronous motor starts as a low-efficiency induc¬ 
tion motor, it follows that it will not start under load, but will 
develop only enough torque to pull itself into synchronism. 

The usual method of starting a synchronous motor is as fol¬ 
lows: A starting compensator with several taps is provided, which 



Fig. 63. 600 K.V. A. Self-Starting Synchronous Condenser 

Courtesy of Westinghouse Electric and Manufacturing Company 


may reduce the voltage applied to the stator of the motor to a 
value of from 50 to 70 per cent of normal line voltage, depending 
upon the amount of current required to bring the motor to about 
95 per cent of synchronous speed. At this speed the field switch 
may be closed and the current in the field adjusted to about 
correct value. The full-line voltage may then be applied to the 
motor, when it will pull into synchronism. It will then be neces¬ 
sary to adjust the strength of the field to a value depending on 


290 


MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY G7 

whether the machine is to operate as a motor or as a synchronous 
condenser. 

Some manufacturers recommend starting synchronous motors 
with the field short-circuited through a resistance. This is usually 
accomplished by making the discharge resistance heavy enough so 
that it will stand the induced current in the fields. In that case 
the field switch is left in the discharge clips during starting. The 
synchronous motor may be brought up to speed by an auxiliary 
starting motor and synchronized on the system, just as already 
described under the subject of a. c. generators. 



Fig. 64. 1200 Kw. Synchronous Motor-Generator Set 

Courtesy of Crocker-Wheeler Company 


Speed. The speed of a synchronous motor depends only on 
the frequency and is constant for a given frequency up to a certain 
point. If loaded beyond this point, the motor “pulls out”, or 
comes to rest. 

Uses of Synchronous Motors. Driving Generators. The most 
usual application of synchronous motors is for driving d. c. or a. c. 
generators. They are largely used for driving d.c. generators for 
railway, lighting, and power service because of their good speed 


291 


68 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

characteristics. In such cases they are usually direct-connected to 
the generator and mounted on the same base with it, Fig. 64. In 
cases where it is necessary to obtain current at a frequency differ- j 
ing from the supply circuit, synchronous motors of one frequency 
are connected to a. c. generators of another frequency. Such com¬ 
binations are called “frequency changer sets”. Where the ma¬ 
chines are direct-connected and therefore have the same speed, 
the ratio of poles on the two machines must correspond to the 
ratio of frequencies desired. 



Fig. 65. General Electric Synchronous Condenser with Direct-Connected Exciter 


Driving Compressors, Blowers, Etc. Synchronous motors are 
also well adapted for direct connection to some types of machines, 
such as air compressors and blowers. The speeds which can be 
obtained are well suited to such machines and considerable fly¬ 
wheel effect can be obtained, which is also of advantage. 

Synchronous Condensers. Another very useful application 
of synchronous motors is their use as synchronous condensers. In 
any of the applications mentioned above, the field strength of the 
motor can be increased until the motor is taking leading current 
from the line. Thus instead of decreasing the general power factor 
of the system, as is the case with the induction motor, these motors 
may be made to increase the power factor of the system. 


292 





MANAGEMENT OP DYNAMO-ELECTRIC MACHINERY 69 


Where the motor is driving other load, this corrective effect 
must necessarily be but a small part of the total capacity of the 
machine. If the motor be floated on the line without carrying any 
mechanical load except its own rotor, a proportionally larger cor¬ 
rective effect can be obtained. A machine operated in this way 
is called a “synchronous condenser”. In many installations hav¬ 
ing a large number of induction motors with a low average load, 
the power factor is very low. The increased capacity made avail¬ 
able from the generators by increasing the power factor will often 
warrant a considerable investment in synchronous condensers in 
such cases. Pig. 65 shows a General Electric synchronous con¬ 
denser with exciter which may be used under such condition^. 
The sole purpose of these machines is to raise the general power 
factor of the system. 


OPERATION 

Directions for Running Generators and Motors. Preliminary 
Bun with No Load. If possible, a new machine should be run with 
no load or with a light one for several hours. It is bad practice 
to start a new machine with its full load or even a large fraction 
of it. This is true even if the machine has been fully tested by 
its manufacturer and is apparently in perfect condition, because 
there may be some fault produced in setting it up, or some other 
circumstance that would cause trouble. All machinery requires 
some adjustment and care for a certain time to get it into smooth 
working order. 

Voltage and Current Regulation. A generator requires that 
its voltage or current should he observed and regulated if it varies. 
The attendant should always be ready and sure to detect and over¬ 
come any trouble, such as sparking, heating, noise, abnormally 
high or low speed, etc., before any injury is caused. Such direc¬ 
tions should be thoroughly committed to memory in order promptly 
to detect and remedy any trouble when it occurs suddenly, as is 
usually the case. If possible, the machine should be shut down 
instantly when any indication of trouble appears, in order to avoid 
injury and to give time for examination. 

Keep Tools Away from Machines. Keep all tools or pieces 


293 




70 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

of iron or steel away from the machine while running. Otherwise, 
they might be drawn in by the magnetism, perhaps getting between 
the armature and pole pieces, thus ruining the machine. 

Commutator and Brushes. Particular care should be given 
to the commutator and brushes, so that the former is kept perfectly 
smooth and the latter are in proper adjustment. Avoid lifting 
brushes when machine is operating, unless there are several in 
parallel. 

Bearings. Touch the bearings occasionally to see whether or 
not they are hot. To determine wdiether the armature is running 
hot, place the hand in the current of air thrown out from it by 
centrifugal force. 

Overloading. Special care should be observed by anyone who 
runs a generator or motor, to avoid overloading it, because this is 
the cause of most of the troubles which occur. 

Personal Safety. The matter of personal safety is of great 
importance in the installation, care, and management of dynamo- 
electric machinery, both from the humanitarian and from the 
financial standpoint. 

Precautions in Handling the Circuit. The safest rule is never 
to touch any conductor carrying current, and never to allow the 
body to form part of an electric circuit, no matter what the volt¬ 
age. This, of course, is a rule which cannot be followed strictly 
in practice. However, every precaution should be taken to prevent 
accidents, and every device which adds to the personal safety of 
the men should be employed. Rubber gloves, rubber shoes, or both, 
should be used in handling circuits of 500 volts or over. Also 
these articles should frequently be tested. Tools with insulated 
handles, or a dry stick of wood, should be used instead of the hand 
for handling the wires. It should always be remembered that a 
wire may be “alive” through some unknown change in connection 
or through accidental contact with another wire, even when it is 
thought to be “dead”. 

High I oltages. On the high a. c. voltages now so common, 
even the above precautions are not sufficient. No work can ever 
be done on such circuits unless they are entirely disconnected 
from all sources of power. In addition, the wires should be thor- 
oughly grounded before being touched. In grounding, the ground 
connection should be first made and last disconnected. 


294 


MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 71 

Stopping Generators or Motors. Operating Alone. A gen¬ 
erator operating alone on a circuit can be slowed down and stopped 
without touching the switches, brushes, etc., in which case the cur¬ 
rent gradually decreases to zero; and then the connections can be 
opened without sparking or any other difficulty. 

Operating in Parallel. However, when a generator is oper¬ 
ating in parallel with other sources of power; it must not be stopped 
or reduced in speed until it is entirely disconnected from the 
system. Furthermore, the current generated by it should be re¬ 
duced nearly to zero before its switch is opened. For a d. e. 
machine this is accomplished by adjusting the field rheostat of the 
machine to be cut out, great care being taken that the change is 
gradual. If the reduction be rapid, the voltage of the machine 
may drop so as to cause a back current. For a.c. generators the 
load is reduced by adjusting the engine governor to reduce the 
input. Field rheostats should not be changed on a.c. generators. 

Constant-Current Generator. A constant-current generator 
may be cut into or out of circuit in series with others, and can 
be slowed down or stopped; or its armature or field coils may be 
short-circuited to prevent the action of the machine, without dis¬ 
connecting it from the circuit. It is absolutely necessary, however, 
to preserve the continuity of the circuit, and not to atteffipt to open 
it at any point, as this would produce a dangerous arc. Hence, a 
by-path must be provided by closing the main circuit around the 
generator, before disconnecting it. This same rule applies to any 
lamp, motor, or other device on a constant-current system. 

Never, except in an emergency, should any circuit be opened 
when heavily loaded; the flash at the contact points, the discharge 
of magnetism, and the mechanical shock are all decidedly objec¬ 
tionable. 

Constant-Potential Motor. A constant - potential motor is 
stopped by turning the starting-box handle back to the first posi¬ 
tion; or, if there is a switch, or circuit breaker, in the circuit, 
as there always should be, it should be opened, after which the 
starting-box handle is moved back to be ready for starting again. 

Immediately after a machine is stopped it should be thoroughly 
cleaned and put in condition for the next run. When not in use, 
machines should be covered with some waterproof material. 


295 



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MANAGEMENT OF DYNAMO- 
ELECTRIC MACHINERY 

PART II 

INSPECTION AND TESTING 

MECHANICAL TESTS 

Adjustment. Adjustment and the other points which depend 
merely upon mechanical construction are hardly capable of being 
investigated by a regular quantitative test, but they can and should 
be determined by a thorough inspection. In fact, a very careful 
examination of all parts of a machine should always precede any 
test. This should be done for two reasons: First, to get the ma¬ 
chine into proper condition for a fair test, and, second, to deter¬ 
mine whether the materials and the workmanship are of the best 
quality and satisfactory in every respect. A loose screw or con¬ 
nection might interfere with a good test; and a poorly fitting 
bearing, brush holder, or other part might show that the machine 
was badly made. 

If it is necessary to take the machine apart for cleaning or 
inspection, the greatest care should be exercised in marking, num¬ 
bering, and placing the parts, in order to be sure to get them 
together exactly the same as before. In taking a machine apart or 
putting it together, only the minimum force should be used. Much 
force usually means that something wrong is being done. A wood 
or rawhide mallet is preferable to an iron hammer, since it does 
not bruise or mar the parts. Usually screws, nuts, and other parts 
should be set up fairly tight, but not tight enough to run any risk 
of breaking or straining anything. Shaking or trying each screw 
or other part with a wrench or screw driver, will show whether 
any of them are too loose or otherwise out of adjustment. 

Friction. Revolving Rotor by Hand. The friction of the 
bearings and brushes can be tested roughly by revolving a small 


297 



74 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

armature or rotor by hand, or slowly by power for a large one, and 
noting if it requires more than the normal amount of force. Excess¬ 
ive friction is easily distinguished, even by inexperienced persons. 
Another method is to revolve the armature and see if it continues 
to revolve by itself freely for some time. A well-made machine in 
good condition and running at or near full speed will continue to 
run for several minutes after the turning force is removed. 

Revolving by Motor. Another method for measuring the fric¬ 
tion of a machine is to run it by another machine used as a motor, 
and determine the volts and amperes required, first , with brushes 
lifted, and, second , with brushes on the commutator with the usual 
pressure. The torque or force exerted by the driving machine is 
afterwards measured by a Prony brake in the manner described 
hereafter for testing torque, care being taken to make the Prony 
brake measurements at exactly the same volts and amperes as were 
required in the friction tests. In this way the torques exerted by 
the driving machine to overcome friction in each of the first two 
tests are determined, and these torques, compared with the total 
torque of the machine being tested, should give percentages not 
exceeding about 2 per cent with the brushes up, or 3 per cent with 
the brushes down. The magnetic pull of the field of the armature 
may be very great, if the latter is not exactly in the center of the 
space between the pole pieces. This would have the effect of in¬ 
creasing the friction of the shaft in the bearings when the field 
is magnetized. It occurs to a certain extent in all cases but it 
should be corrected, if it becomes excessive. This may be tested by 
turning the current into the fields, being sure to leave the armature 
disconnected, and then determining the friction. The friction in 
this case should not be more than 2 to 4 per cent. 

Tests for friction alone should be made at low speed, because 
at high speeds the effects of eddy currents and hysteresis enter 
and materially increase the apparent friction. 

Balance. Perfection of balance of the revolving member of 
a machine is essential. On machines of small or medium size the 
revolving element should be laid on carefully leveled knife-edge 
steel ways. The heaviest side of the rotor will naturally assume 
the lowest position. Balance weights should then be placed diamet¬ 
rically opposite this point until the proper balance is obtained. It 


298 



MANAGEMENT OE DYNAMO-ELECTRIC MACHINERY 75 


does not follow that the static balance will always be the correct 
running balance, and additional balancing may have to be done 
with the machine running at normal speed. 

On very large machines, with which the preceding method 
can not conveniently be used, trial balance weights will have to be 
used until, by repeated tests, the proper position for the correct 
balance weights is obtained. 

Noise. This cannot well be tested quantitatively, although 
it is very desirable that a machine should make as little noise as 
possible. Noise is produced by various causes. The machine should 
be run at full speed, and any noise and its cause carefully noted. 
A machine—especially the commutator—will nearly always run 
more quietly after it has been in use a week or more and has 
worn smooth. 

Heating. Resistance Method. The most accurate way to de¬ 
termine the temperature rise in electrical apparatus is by measure¬ 
ments of resistance, before and after operating, for a specified time 
(usually 4 to 8 hours) under rated load. The rise of tempera¬ 
ture is the percentage increase of initial resistance by the tempera¬ 
ture coefficient for the initial temperature expressed in per cent. 
The standard room temperature or ambient temperature of refer¬ 
ence was formerly 25 degrees centigrade but it is now fixed at 40 
degrees centigrade, corresponding to high temperatures in engine 
rooms and in hot weather. For ordinary tests it may be assumed 
that the resistance of copper increases .4 per cent for each degree 
centigrade rise in temperature, this being correct for 15 degrees 
centigrade, being .385 per cent at 25 degrees centigrade and .364 
per cent at 40 degrees centigrade. 

Thermometer Method. Thermometers are also largely used 
for determining the temperature rise in apparatus. The indica¬ 
tions obtained by thermometer may be about 5 degrees centigrade 
lower than those obtained by the resistance method. When resist¬ 
ance is taken by thermometer, great care should be taken to prevent 
radiation. The thermometer should be covered with a pad of waste 
or cloth, not exceeding two inches in diameter, and allowance 
should always be made for the fact that the temperature is always 
less at the surface than at the interior. 

The American Institute of Electrical Engineers has made 


299 


76 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

general recommendations as to the limits of temperature advisable 
with various kinds of insulating material. Other authorities state 
the limits alloAvable for various types of machinery, for example, 
open and enclosed. 


ELECTRICAL TESTS 

WIRING 

Before any work is done in connection with the installation of 
wires or cables, complete plans should be drawn, showing the proper 
relative location of all apparatus, the size of the conductors in 
every case, and the lengths of the runs. The path of the wires 
will depend on the system of wiring adopted but, in any case, it 
should be as simple and straightforward as possible. The rules of 
the National Board of Fire Underwriters should be closely adhered 
to, as well as the rules of any local board having jurisdiction. It is 
a good plan to have any doubtful points passed on by an inspector 
before the work is completed if the expense involved is very great. 
Otherwise, the work may have to be done over after completion, 
which more than doubles the expense. In general, the Underwriters 
recognize two methods of wiring—“exposed” and “concealed”. 

Exposed Wiring. Exposed wiring on cleats and knobs or, 
for large cables, on cable racks with porcelain insulators is used 
less today than ever before. It has the great advantage of cheap¬ 
ness and accessibility, which will always make it popular in some 
places. However, the wires have an unsightly appearance and 
are subject to injury from sources external to themselves which 
greatly multiply the chances for trouble. 

Concealed Wiring. The use of concrete construction in 
power plants of all kinds, and in industrial plants as well, has 
made it possible to make practically all wiring in such buildings 
concealed in iron, clay, or fiber conduits. Placing the conduits in 
the floors or walls puts the wires entirely out of sight, where they 
are not subject to injury from external sources, and where they 
are usually convenient for connection to the apparatus. Especially 
for power houses this method has become practically universal. 

Houses, Office Buildings, Etc. The wiring of houses, office 
buildings, factories, etc., is practically all placed in conduits, as 


300 


MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 77 


stated above. The voltage in all such cases is low; that is, usually 
not over 600 volts. The wires are insulated with rubber, paper, 
or varnished cambric of the thickness necessary for the voltage 
used, and are covered with braid if installed in dry locations. If 
moisture is likely to be encountered, the wires are covered with 
a lead sheath. 

Power Houses .* In power houses similar construction is used 
for voltages up to and including 13,200 volts. For busbars, espe¬ 
cially when enclosed in fireproof compartments, bare bar or rod 
is usually used. For voltages above 13,200 there are many installa¬ 
tions where the wires are insulated even up to 33,000 volts. How¬ 
ever, insulation for such potentials is considered by most engineers 
as false protection. That is, it is not safe to depend upon the 
insulation to protect one against shock, and its presence is apt 
to give to the operator a false sense of security which might cost 
him his life. It has, therefore, become an almost universal practice 
to make all station wiring for high voltages of bare wire mounted 
on porcelain insulators. With such construction it is evident that 
one must never come near the wires, and the result is that the 
wiring is safer than if it were insulated. 

When alternating-current conductors are enclosed in iron con¬ 
duits, both wires of each phase, or all the wires, must be run in 
the same duct; otherwise the inductance would be excessive. 

Size of Conductors. All conductors, including those con¬ 
necting the machine with the switchboard, as well as the busbars 
on the latter, should be of ample size to be free from overheating 
and excessive loss of voltage. The voltage drop between the gener¬ 
ator and the switchboard should not exceed one-half per cent at full 
load. Excessive drop at this point interferes with proper regula¬ 
tion and adds to the less easily avoided drop on the distribution 
system. 

The safe-carrying capacities of copper conductors as recom¬ 
mended by the National Board of Fire Underwriters are given in 

Table II. . 


301 


78 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

TABLE II 

Safe=Carrying Capacities of Copper Wires 


Rubber Insulation 

Other Insulations 

B. & S. G. 

Amperes 

Amperes 

Circular Mils 

18 

3 

5 

1,624 

16 

6 

8 

2,583 

14 

12 

16 

4,107 

12 

17 

23 

6,530 

10 

24 

32 

10,380 

8 

33 

46 

16,510 

6 

46 

65 

26,250 

5 

54 

77 

33,100 

4 

65 

92 

41,740 

3 

76 

110 

52,630 

2 . 

90 

131 

66,370 

1 

107 

156 

83,690 

0 

127 

185 

105,500 

00 

150 

220 

133,100 

000 

177 

262 

167,800 

0000 

210 

312 

211,600 

Circular Mils 




200,000 

200 

300 


300,000 

270 

400 


400,000 

330 

500 


500,000 

390 

590 


600,000 

450 

680 


700,000 

500 

760 


800,000 

550 

840 


900,000 

600 

920 


1,000,000 

650 

1,000 


1,100,000 

690 

1,080 


1,200,000 

730 

1,150 


1,300,000 

770 

1,220 


1,400,000 

810 

1,290 


1,500,000 

850 

1,360 


1,600,000 

890 

1,430 


1,700,000 

930 

1,490 


1,800,000 

970 

1,550 


1,900,000 

1,010 

1,610 


2,000,000 

1,050 

1,670 



The lower limit is specified for rubber-covered wires to prevent gradual 
deterioration of the high insulations by the heat of the wires, but not from 
fear of igniting the insulation. The question of drop is not taken into con¬ 
sideration in the above tables. 

The safe-carrying capacity of insulated aluminum wire is 84 per cent of 
that given for copper wires of corresponding size and insulation. 


302 
























MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 79 

PROTECTIVE APPARATUS 

Switches. Switches are devices for closing or opening a 
circuit. Several different kinds are used, the design depending 
upon the character and the severity of the service. For low volt¬ 
age circuits (125 or 250 volts) of 10 amperes or less, snap switches 
are often used. These switches are usually of the kind mounted 
on porcelain bases and enclosed with a metal cover. The handle 
operates on a spring which in turn operates the contact blade or 
blades. Thus the contacts remain in position until the spring pres- 



Fig. 60. Exploded View of Double-Pole Lever Switch 
Courtesy of General Electric Company 


sure overcomes the friction, when the switch opens or closes with 
a quick snapping action. 

Lever Switches. Lever or knife switches consist of blades of 
copper operating in clips attached to copper blocks. One end of 
the blade is hinged in the clips and spring washers are provided 
to insure pressure enough for good contact and to take up any wear 
between blade and clips. An insulating handle is attached to the 
other end of the blade. If the switch has two or more poles, they 


303 







80 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

are fastened together by means of an insulating crossbar; and the 
handle is attached to the crossbar instead of to the blade direct. 
Fig. 66 shows such a lever switch for mounting on a switchboard.* j 
It also shows an exploded view of the parts. 

The general construction, spacing, etc., is, in .this country, 
fixed by the rules of the National Board of Fire Underwriters. 


Fig. 67. Complete Panel Board in Steel Cabinet 

Their rules require that switches have sufficient metal for the neces¬ 
sary mechanical strength, and that the temperature rise shall not 
be more than 28 degrees centigrade above the surrounding air, when 
carrying full rated load continuously. With good contacts they 
allow a rated current density of 75 amperes for each square inch of 
contact area. Switches of over 30 amperes must be provided with 
terminal lugs screwed or bolted into the switch into which the 


304 










MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 81 

conducting wires must be soldered. In practice, lever switches of 
less than 30-ampere capacity are seldom manufactured and, on 
that size, lugs are usually furnished. 

Lever switches should be mounted on non-absorptive non¬ 
combustible insulating bases or panels such as slate, marble, or 
porcelain. Where switches are mounted on bases which are to be 
placed against a flat surface, the connection must be made at the 
front of the switch. In this case the block is extended far enough 
so that the terminal can be screwed or bolted on to the face of the 
block. Where the switches are mounted on switchboard panels, a 
stud is passed through the panel from the switch block and the 
terminals are fastened to it by means of nuts. 

Lever switches should be mounted so that gravity tends to 
open them rather than close them. They should be grouped as far 
as possible for ease of operation. They should be easily accessible 
and located in a dry place. Modern practice requires that, for 
small capacities and especially when in exposed places, the group 
of switches be mounted on a panel board and placed in a steel 
cabinet properly lined with some material such as slate, Fig. 67. 

Plain lever switches are not used for opening circuits under 
load on more than 300 volts d. c. or 500 volts a. c. However, they 
may be used on circuits of all voltages for disconnecting purposes 
at no load or very small load and where any considerable current 
is ruptured by some other device. 

The Underwriters’ Rules cover a large number of points of. 
design and construction • not mentioned above, but they are of 
interest principally to the manufacturers, and all reputable manu¬ 
facturers follow them. 

Oil Switches. For alternating-current circuits, especially 
where the voltage is high, lever switches are not suitable for opera¬ 
tion under load. An oil switch is one in which the circuit is made 
or broken under oil. Fig. 68 shows a single-pole 15,000-volt oil 
switch for switchboard service, with the oil tank removed. Such 
switches are mounted back of, or remote from, the panels, and 
are operated by a handle connected to the switch through a system 
of links and levers. These switches usually open by gravity, either 
when tripped by hand or automatically. When tripped auto¬ 
matically by abnormal conditions in the circuit, they are sometimes 


305 



82 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

called “oil circuit breakers”. They are manufactured with one or 
more poles, sometimes with one tank for all poles and sometimes 
with a separate tank for each pole. 

Switches built along the same general lines are also manu¬ 
factured for mounting on walls or on motor-driven machines and 
are used for controlling individual motors. In textile mills and 
other places where the fire risk is great, such switches are almost 
essential even on low-voltage circuits. 


Fig. 68. General Type of Oil Switch with Cover Removed 
Courtesy of General Electric Company 

Oil switches are not suitable for use on direct-current circuits, 
since there is no reversal of current and the arc is much harder to 
extinguish than the a. c. arc. 

Circuit Breakers. Where large currents are to be broken, 
when the voltage is high, or where automatic features are required, 
the usual direct-current practice is to use circuit breakers. For 
electric railway service on cars, or in places where the equipment 


306 







MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 83 

must be totally enclosed, magnetic blowout circuit breakers are still 
used. These breakers are arranged so that, as the circuit is broken, 
current is caused to flow in a coil which produces a magnetic field 
so placed as to draw out the arc and cause it to break quickly. 

The most common form of circuit breaker is the carbon-break 
circuit breaker as illustrated in Fig. 69. This breaker has a copper- 


Fig. 69. “ Type C ” 650-Volt 2000-Ampere Single-Pole Overload Circuit Breaker 

Courtesy of General Electric Company 

leaf brush for continuously carrying the current. As the circuit 
breaker is opened, or opens automatically, this brush leaves contact 
first. The current is then temporarily carried by a secondary cop¬ 
per contact which opens second. Last of all the carbon contacts 
open and actually break the circuit. This arrangement insures that 
the burning will all come on the renewable carbon block and the 
main contacts will always be left in good condition. 


307 





84 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

Automatic overload tripping is obtained by arranging a mag¬ 
netic circuit in such a way that at a predetermined current value 
an armature will be lifted and, in its movement, will strike a trip¬ 
ping latch which in turn releases the moving element of the breaker 
so that it opens by gravity and the spring action of the contacts. 
Other automatic features can also be obtained by means of auxiliary 
attachments or separate relays acting on the circuit-breaker mech¬ 
anism in a similar way. Thus the circuit breaker may be tripped 
by an underload, by low voltage, of by the reversal of current, 
when desired. 

Carbon-break circuit breakers are often used in alternating- 
current circuits for voltages of 600 and below. They are of the 
same general appearance as those used in direct-current circuits, 
and operate on the same principle. 






fj o o J> 

| o 

^ lO °hP 







101-200AMPERES 2S0 VOLTS 
Eig. 70. Section of Enclosed Fuse 


Fuses. Because of the great expense of replacements on 
circuits where trouble is frequent and severe, fuses are being 
abandoned in favor of circuit breakers for all large power circuits. 
However, there are so many places where fuses have the advantage, 
because they are simpler, that they may still be considered among 
the most important protective devices used. 

A fuse is merely a strip of metal, inserted in a circuit, of such 
cross section that at a given current it will melt, thus opening the 
circuit. If this fuse is made so that its ultimate carrying capacity is 
less than the safe-carrying capacity of the rest of the circuit, it will 
protect the apparatus against the excessive current. This in gen¬ 
eral describes the principle and function of the fuse. 

The form which a fuse may assume depends upon the severity 
of the service, the capacity of the circuit, and the voltage. Figs. 70, 
71, and 72 show, respectively, a section of a National Electric Code 


308 




























MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 85 


Standard enclosed fuse, an open-link fuse, and an expulsion fuse for 
higher voltage a. c. circuits. 

Open-link fuses are, as the name implies, merely links of metal 
with limited current-carrying capacity, which are mounted between 
two terminal blocks and fastened to them by bolts or screws. The 
metal used is usually an alloy of 
special composition for the serv¬ 
ice. The National Board of Fire 
Underwriters* requires that the 
fuses be stamped with about 80 
per cent of the maximum cur¬ 
rent which they can carry indefinitely, thus allowing about 25 per 
cent overload before the fuse melts. The minimum current which 
will melt the fuse in about five minutes is taken as the melting point. 

It can readily be seen that on circuits of large capacity, or 
circuits having a large generating capacity back of them, the open¬ 
ing of an open-link fuse would produce a heavy flash and a dan- 



Fig. 71. Open-Link Fuse 


gerous splashing of metal. The use of enclosed 
fuses on circuits of from 30- to 600-ampere capac¬ 
ity has become almost universal and this practice 
is to be recommended in any case where fuses are 
obtainable which meet the rules of the Under¬ 
writers. The Underwriters’ Rules cover the gen¬ 
eral construction, performance, and dimensions 
of fuses within the range of capacities given 
above. 

Fuses should always be employed when the 
size of the wire changes, or where connections 
between any electrical apparatus and the con- 
Fig. 72. General Eiec-ductors are made. They must be mounted on 
t puisSn g Fufe 0 l Biock' slate, marble, or porcelain bases; and all metallic 
fittings employed in making electrical contacts 
must have sufficient cross section to insure mechanical stiffness and 



carrying capacity. 

For higher voltage circuits used in alternating current, the 
open fuse has the same objections as for direct current and in a 
more marked degree. The completely enclosed fuse is also found 
unsatisfactory. It has, therefore, been necessary to adopt a differ- 


309 














86 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

ent principle of operation for these fuses. The link of metal used 
for the fuse is enclosed in a tube which has an enlarged section at 
one end and is open at the other end. The reduced section of the 
fuse is placed so as to come within the enlarged section, or explosion 
chamber of the tube. When the fuse is ruptured, gases form in 
the explosion chamber which blow out through the tube, thus open¬ 
ing the circuit quickly and effectively. 

As a general proposition, fuses of any kind are superfluous or 
undesirable where the conditions warrant the use of automatic 
circuit breakers, as in power houses, sub-stations, and factories. 
The conditions which should be met in the manufacture of a good 
fuse are as follows: 

(1) They should melt at a definite current. 

(2) The melting point should not change due to time, current, 
heating, or any reasonable service conditions. 

(3) They should act quickly at the current for which they are 
marked. 

(4) They should give firm and lasting contacts with the ter¬ 
minal blocks to which they are attached. 

While the above conditions are hard to meet and perfect fuses 
cannot be expected, they do give a fair degree of protection and 
will continue to be used for many classes of service. 


ELECTRICAL RESISTANCE 

Among the most important tests which it is necessary to make 
in connection with dynamo-electric machinery are those for resist¬ 
ance. There are two principal classes of resistance tests that must 
be made in connection with generators and motors: first, the resist¬ 
ance of the wires or conductors themselves, called the metallic 
resistance; and second, the resistance of the insulation of the wires, 
known as the insulation resistance. The latter should always be as 
high as possible, because a low insulation resistance not only allows 
current to leak, but also causes “burn-outs” and other accidents. 
Metallic resistance, such, for example, as the resistance of the 
armature or field coils, is commonly tested either by the Wheat¬ 
stone bridge or by the “drop” (fall-of-potential) method. 


310 


MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 87 

Metallic Resistance 


Wheatstone Bridge Method. The Wheatstone bridge is sim¬ 
ply a number of branch circuits connected as indicated in Fig. 73. 
A y By and C are resistances the 
values of which are known. X 



is the resistance which is being 
measured. G is a galvanometer, 
S its key, and E is a battery of 
one or two cells controlled by a 
key K, all being connected as 
shown. The resistance C is 
varied until the galvanometer 
shows no deflection when the 



keys K and S are closed in the pig. 73 , Wheatstone Bridge Diagram 
order named. If the key 8 

should be closed before K , or at the same moment, the inductive 
effect might produce a pronounced deflection of the galvanometer 


needle, and thus probably cause con¬ 
fusion. The value of the resistance X 
is then found by multiplying together 
resistances C and B, and dividing by 
A; that is, 




Portable Bridge. A very con¬ 
venient form of this apparatus is 
what is known as the portable bridge, 
Fig. 74. This consists of a plug re¬ 
sistance box of the decade type, cor- 


Fig. 74. Portable Wheatstone 
Bridge 


Courtesy of Roller-Smith Company responding to C of Fig. 73; the ratio 
coils corresponding to A and B of Fig. 73, four of these coils being 
multipliers and four dividers, giving a theoretical range from 
.001 ohms to over 11 megohms; sensitive galvanometer, battery, 
keys, etc. The resistance coils are of zero temperature coefficient 
and are noninductively wound. For the method of operation, the 
reader is referred to the article on Electrical Measurements. The 
Wheatstone bridge may be used for testing the resistances of 


311 













88 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


almost any field coils that are found in practice. In measuring 
field resistances with the bridge, care must be taken to wait a con¬ 
siderable time after pressing the battery key, before pressing the 
galvanometer key, in order to'allow time for the self-induction of 
the magnets to disappear. 

Where the resistance of a generator armature, say, is too high 
for accurate bridge measurements, recourse may be had to an 
ohmmeter, or a bridge megger, both instruments of which are 
described in the article on Electrical Measurements. The method 
described in the following paragraph is also available. 

Drop, or Fall-of-Potential, Method. The fall-of-potential 
method is well adapted for locating faults quickly and for testing 
the armature resistance of most generators and motors, or the 
resistance of contact between commutator and brushes, or other 
resistances which are usually only a few hundredths or even thou¬ 
sandths of an ohm. This method consists in passing a current 
through the armature and connections and a known resistance of 
say 1/100 ohm, all connected in series, as represented in Fig. 75. 
The ‘ ‘ drop ’ ’ or fall-of-potential in the armature and that in the 
known resistance are compared by connecting a voltmeter first to 
the terminals of the known resistance (marked 1 and 2), and then 
to various other points on the circuit, as indicated by the dotted 
voltmeter terminals at M, N, 0, Q, R, and S, so as to include suc¬ 
cessively each part to be tested. The deflections in all cases are 
directly proportional to the resistances included between the points 
touched by the terminals. The current needed depends upon the 
resistance of the circuit and the sensitiveness of the voltmeter. 
A resistance is used for limiting the current, which may be obtained 
from an ordinary 110- or 220-volt source of d.c. supply. 

Instead of using a known resistance, an ammeter may be 
inserted in series with the resistance to be tested, the latter being 
then determined by Ohm’s law, viz., If E is the voltmeter deflection 
and 1 represents the amperes flowing, the resistance of the part 
under test is 


A “station” or a portable voltmeter may be used for the 
readings, and its terminals may be held in the hands, or they may 


312 


MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 89 

be conveniently arranged to project from an insulating handle like 
a two-pronged fork. Usually 10 to 100 amperes and a low-reading 
voltmeter are needed for low resistances. 

It is well to start with a small testing current, increasing it 
until a good deflection is obtained on the voltmeter. If a current 
of several amperes cannot be had, a few cells of storage battery or 
some strong primary battery can be used with a galvanometer or 
low-reading voltmeter. 

The diagram indicates the testing of a machine with series 
fields. Shunt fields, on account of their high resistance, may be 
tested by the bridge method, or by voltmeter and ammeter read- 


Mains 110 
JL 


Fig. 75. Wiring Diagram for “ Drop ” Method of Testing Armature Resistance 

ings; while the armature can be tested, as in Fig. 75. Of course 
it must not be allowed to revolve while its resistance is being tested. 

The drop method of testing is also very useful in locating 
any fault. The two wires leading from the voltmeter are applied 
to any two points of the circuit, as indicated by the dotted lines, 

Fig. 75_for instance, to two adjacent commutator segments, or to- 

a brush tip and the commutator; any break or poor contact will be 
indicated immediately by the deflection being larger than at some 
other similar part. This shows that the fault is between the two 
points to which the wires are applied. Thus, by moving these along 
on the circuit, the exact location of any irregularity, such as a bad 
contact, short circuit, or extra resistance, can be found. 


The res/stance of any 
parts of the circuit in¬ 
ducted between the vott- 
mefer termina/s as in¬ 
dicated at M.N. O.O.R 
S. etc i, are to each other 
as the corresponding 
defiections 




Vo/tmeter 


Vo/tmeter termina/s 


These are appi/ed 
at any points of the 
Circuit which are 
to be tested as in¬ 
dicated at M.N.O, 
O, R.S, etc. 


Lamp bank for 
controtting test¬ 
ing current 
from mains 


R S 

R & S shou/d be egua/ 


313 












90 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 
Insulation Resistance 

The insulation resistance of a generator or motor, that is, the 
resistance between its conductors and its frame, should be suffi¬ 
ciently high so that not more than one-millionth of its rated current 
will pass through it at normal voltage. Any value over one megohm 
in such cases is usually high enough. It is therefore beyond the 
range of ordinary Wheatstone bridge tests; but two good methods 
are applicable, the ‘ ‘ direct-deflection ’ ’ method and the voltmeter 
method. 

Direct-Deflection Method. The direct-deflection method is 
carried out by connecting a sensitive galvanometer, such as a 
Thomson high-resistance reflecting galvanometer, in series with a 
known high resistance, usually a 100,000-ohm rheostat, a battery, 



and keys, as shown in Fig. 76. The galvanometer should be shunted 
with the 1/999 coil of the shunt, so that only 1/1000 of the current 
passes through the galvanometer, the machine being entirely dis¬ 
connected. The keys A and B are closed and the steady deflection 
noted. It is well to use but one cell of the battery at first, and 
then increase the number, if necessary, until a considerable deflec¬ 
tion is obtained. The circuit is then opened at the key B and con¬ 
nected by wires to the binding post or commutator and to the 
frame or shaft of the machine, as indicated by dotted lines, so that 
the machine insulation resistance is included directly in the circuit 
with the galvanometer and the battery. The key A is then closed 
and the deflection noted. Probably there will be little or no deflec¬ 
tion on account of the high insulation resistance; and the shunt is 
changed to 1/99, 1/9, or left out entirely, if little deflection is 
obtained. In changing the shunt, the key should always be open; 
otherwise the full current is thrown on the galvanometer. The 
insulation is then calculated by the formula: 


314 
















MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 91 


Insulation resistance = 


DRS 

d 



in which D is the first deflection without the machine connected; 
d is the deflection with the machine insulation in the circuit; R is 
the known high resistance; and S is the ratio of the shunted current 
through the galvanometer. If the shunt is l/999,in the first test, 
and 1/9 in the second, 8 is 100. If the shunt is disconnected en¬ 
tirely in the second test, 8 is 1000. It is safer to leave the high 
resistance in circuit in the second test to protect the galvanometer 
in case the insulation resistance is low. Therefore this resistance 
must be subtracted from the result to obtain the insulation of the 
machine itself. 

By the above method it is possible to measure 100 megohms or 
even more. The wires and connections should be carefully 
arranged to avoid any possibility of contact or leakage which would 
spoil the test. If no deflection is obtained, place one finger on the 
frame and one on the 


binding post of the ma¬ 
chine, which makes 
enough leakage to affect 
the galvanometer and 
show that the connec¬ 
tions are right, thus 
proving that any poor 
insulation will be indi¬ 
cated, if it exists. 

Voltmeter Method. 

The voltmeter test for 
insulation resistance re¬ 
quires a sensitive high- 
resistance voltmeter. 

Take, for example, the 
150-volt instrument, Fig. 

77, which usually has about a 15,000-ohm resistance, (A certifi¬ 
cate of the exact resistance is pasted inside each case.) Apply it 
to some circuit or battery and measure the voltage. This should 
be as high as possible, say 100 volts. The insulation resistance of 


Fig. 77. Typical D’Arsonval Voltmeter 
Courtesy of General Electric Company 


315 




92 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

the machine is then connected into the circuit, as indicated in 
Fig. 78. The deflection of the voltmeter is less than before, in 
proportion to the value of the insulation resistance. The insula¬ 
tion is then found by the equation: 

DR „ 

Insulation resistance = — 7 — iv 
a 

in which D is the first deflection; d is the second deflection; and 
R is the resistance of the voltmeter. If the circuit is 100 volts, D is 
100 ; and if d, the deflection through the insulation resistance of 



the machine, is 1 division, the insulation is 1,485,000 ohms. Perma¬ 
nent marks indicating amounts of insulation may be put on the 
voltmeter scale. When making measurements, the voltage should 
be the same as that employed in preparing this scale, say 115 volts. 
To calculate the scale use the formula 

, 115 R 

d= XTB 

in which X is the insulation resistance (1 megohm, ^ megohm, 
etc.); and d is the number of volts, opposite which the correspond¬ 
ing graduation is to be placed to form the new scale. This method 
does not test exceedingly high resistances; but if little or no deflec¬ 
tion is obtained through the insulation resistance, it shows that the 
latter is at least several megohms—which is high enough for most 
practical purposes. 

Magneto-Electric Bell. The ordinary magneto-electric bell 
may be used to test insulation by simply connecting one terminal 
to the binding-post of the machine and the other to the frame or 
shaft. A magneto bell is rated to ring with 10,000 to 30,000 


316 




















MANAGEMENT OP DYNAMO-ELECTRIC MACHINERY 93 


ohms in series with it, and if it does not ring, it shows that the in¬ 
sulation is more than that amount. This limit is altogether too low 
for proper insulation in any case, and therefore this test is rough, 
and really shows only whether or not the insulation is very poor or 
the machine practically grounded. 

The magneto is also used for “continuity’’ tests, to determine 
whether a circuit is complete, by simply connecting the two ter¬ 
minals of the magneto to those of the circuit. If the bell can be 
rung, it shows that the circuit is complete; if not, it indicates a 
break. An ordinary electric bell and cell of battery can be used in 
place of the magneto. 


DIELECTRIC STRENGTH TESTS 

The above methods of determining insulation are given in 
some detail, since they give a means of testing which can be applied 
almost any place. However, the ohmic resistance of any insula¬ 
tion is not of first importance. The dielectric strength, that is, 
the resistance to actual rupture by high voltage current, is con¬ 
sidered as much more important. In making such tests, the high 
voltage should be applied between every circuit of the apparatus 
and every other circuit, and between every circuit and the material 
of the machine itself. 

Test Voltages for Different Sized Machines. The rules of 
the American Institute of Electrical Engineers recommend that 
the proper voltage to be used for testing machines in general shall 
be twice the normal voltage of the circuit to which they are con¬ 
nected, plus 1000 volts. There are a few exceptions. 

Conditions of Test. The machine should be tested with an 
alternating voltage of a virtual value (the ordinary a. c. voltmeter 
gives this value very closely), as given above. The frequency 
is not important on direct-current apparatus or on alternating- 
current apparatus of small capacity. However, on large a.c. 
machines the frequency should be the same as the normal fre¬ 
quency at which the machine is to operate. 

Before being given high potential tests, all machines should 
be completely assembled, should be clean and in good running 
condition, and should be at a temperature corresponding to full 


317 


94 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

load on the machine. The rules of the A. I. E. E. specify that the 
high-potential tests shall ordinarily he made in the factory of the 
manufacturer. A number of other rules are given in regard to 
“methods of testing”, “methods of measuring the test voltage”, 
and “apparatus for supplying the test voltage”. These rules are 
followed almost universally in the United States today, as are the 
other rules of the A. I. E. E. 

VOLTAGE 

Voltmeter. An instrument used to measure the pressure or 
voltage of a circuit is called a voltmeter, Fig. 77. It is usually a < 
galvanometer of practically constant resistance. The moving ele- ; 
ment carries a pointer which moves over a graduated scale. This 
scale is marked directly in volts or millivolts. A voltmeter should 
have a very high resistance in order that the indications may always 
be accurate and that the instrument may take as little current as 
possible. It should be shielded so that it will not be affected by 
stray fields due to magnets or currents flowing in conductors close • 
to the instrument. 

Test Method. The voltage of any machine or circuit is 
tested by merely connecting the two terminals of the voltmeter to 
the two terminals or conductors of the machine or circuit. To get 
the external voltage of a generator or motor, the voltmeter is 
usually applied to the two main terminals or brushes of the 
machine. This external voltage is what a generator supplies to the 
circuit. It is also called the difference of potential, or terminal 
voltage, and is the actual figure upon which calculations of the 
efficiency, capacity, etc., of any machine are based. 

A generator for constant*potential circuits should, of course, 
give as nearly as possible a constant voltage. A plain shunt 
machine usually falls from 5 to 15 per cent in voltage when its 
current is varied from zero to full load. This is due to the i. r. 
drop caused by the resistance of the armature circuit, which, in 
turn, weakens the field current and magnetism. Armature reaction 
usually occurs also, and still further lowers the external voltage. 
This variation is undesirable, and is usually avoided by regulating 
the field magnetism (varying the resistance in the field circuit) 


MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 95 

or by the use of compound-wound generators. Compound-wound 
generators may be designed to give practically constant voltage 
from no load to full load, or they may be designed to rise any de¬ 
sired percentage of “over-compounding” from no load to full load. 


CURRENT 

Instruments for measuring current are called “ammeters”. 
These instruments are built on the same general principle as a 
voltmeter, except that the main line current or a shunted part of it 
passes through the instrument. 

Ammeter Always Connected in Series with Line. In testing 
the current of a generator or motor, it is necessary only to connect 
an ammeter of the proper range in series with the machine to be 
tested, so that the whole current passes through the instrument or 
its shunt. To test the current in the armature or the field alone, 
the ammeter is connected in series with the particular part. To 
avoid mistakes in the case of a shunt-wound generator, it is well to 
open the external circuit entirely in testing the current used in the 
field coils; for the same reason the brushes of a shunt motor should 
be raised before testing the current taken by the field.* In a 
constant-current, or series-wound, machine the same current flows 
through all parts as well as through the circuit; consequently the 
measurement of current is very simple. 

If an ammeter cannot be had, current can be measured by 
inserting a known resistance in the circuit and measuring the dif¬ 
ference of potential between its ends. The volts thus indicated, 
divided by the resistance in ohms, give the number of. amperes 
flowing. If a known resistance is not at hand, the resistance of a 
part of the wire forming the circuit can be calculated from its 
diameter measured with a screw caliper or a wire gage, by referring 
to any of the tables of resistances of wires; or the resistance can be 
measured by a Wheatstone bridge, Fig. 74. 

The above methods will seldom be found necessary in modern 
plants of any kind, since good portable ammeters are now so cheap 
as to be included in the equipment of nearly all such plants. In 

* These instructions are to be followed when only one ammeter is to be had ; 
otherwise one could be placed in the field circuit and another in the circuit from 
the starting box to the independent armature terminal. 


319 



96 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

many industrial plants, especially those using alternating current, 
it is the practice to put an ammeter on each motor circuit perma- f 
nently. In central stations all machines and most feeder circuits 
are provided with ammeters for reading the line current. 

Water Box for Testing Generators. In testing a generator 
at full load it is often difficult to find a means of disposing of the I 
current generated. Any metallic resistance designed to absorb 
the entire output of a large generator would be out of the question 
because of the expense. If there is no way to absorb the power by 
connecting the machine to actually loaded distributing lines, a 
water box forms the cheapest means. The size of the box will, of 



Fig. 79. Wiring Diagram for “ Pump Back ” Testing Method with Mechanical 
Loss Supply 


course, depend upon the size of the machine to be tested. For 
machines of medium size a tub, barrel, or hogshead may be used. 
This is filled with water, and salt or common baking soda added 
until the proper current is obtained when the terminals are lowered 
into it. These terminals are usually two plates of iron to which 
the main conductors are attached. This arrangement allows the 
current to be varied by raising and lowering the plates, by adjust¬ 
ing the distance between plates, or by changing the strength of the 
solution. Alternating-current generators, when tested in this way, 
will require two, three, or four plates, depending on whether they 
are single-phase, three-phase, or two-phase. 

“Pump Back” Method. In some cases, where duplicate 
machines are to be tested, another method is available. The two 


320 

















MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 97 


machines are connected together both electrically and mechanically. 
Thus one machine, acting as a motor, drives the second machine 
mechanically; while the second machine, acting as a generator, 
drives the first machine electrically. Of course such a combination 
must be supplied with some other power to furnish the losses in 
the two machines. This can be done by belting another motor, 
operated from an outside source, to the two machines in test, Fig. 79. 



Fig. 80. Wiring Diagram for “ Pump Back ” Testing Method with Electrical 
Loss Supply 


This auxiliary motor may be comparatively small since it supplies 
the losses only. With such an arrangement, one of the machines can 
be given full load and tested completely without the use of water 
boxes and without requiring a large amount of power to operate it. 

In another of the 4 'pump back” methods, there is an electrical 
loss supply instead of a mechanical loss supply. Fig. 80 shows the 
method of wiring the machines for such a test. 

Similar methods may be employed for testing duplicate a.c. 
machines. Modification will have to be made, of course, to take 
care of the difference in the character of the current. 


SPEED 

Speed Counter. Speed is usually measured by the well-known 
speed counter, Fig. 81, consisting of a small spindle which turns a 
wheel one tooth each time it revolves. The point of the spindle is 


321 
















98 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


held against the center of the shaft of the generator or motor for a 
certain time, say one minute or one-half minute, and the number of 
revolutions is read off from the position of the wheel. 




Tachometer. Another instrument for testing the number of 
revolutions per minute is the tachometer. The stationary form of 

this instrument is shown in Fig. 
82. It must be belted by a string, 
tape, or light leather belt to the 
machine, the speed of which is to 
be tested. If the sizes of the pul¬ 
leys are not the same, their speeds 
are inversely proportional to their 
diameters. The portable form of 
this instrument, Fig. 83, is applied 
directly to the end of the shaft 
of the machine, like the speed 
counter, a sliding gear shifter 
providing the required range of 
speeds. These instruments pos¬ 
sess the great advantage over the 
speed counter that they instantly 
point on the dial to the proper 
speed, and they do not require to 
be timed for a certain period. 

Electric Tachometer. Another 
instrument which gives a direct 
reading of revolutions per minute 
is the electric tachometer. This 
instrument consists of a small generator, which is driven by 
the revolving shaft, and a voltmeter connected across the ter- 


Fig. 82. Stationary Form of 
Tachometer 

Courtesy of James G. Biddle, 
Philadelphia 


322 










MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 99 


minals of this generator. The design is such that the voltage of 
the generator is proportional to its speed. The voltmeter is cali¬ 
brated in revolutions per minute and is, therefore, a direct-reading 
tachometer. 

A simple way to test the speed of a belted machine in revolu¬ 
tions per minute is to make a large black or white mark on the 
belt and note how many times the mark 
passes per minute; the length of the belt 
divided by the circumference of the pulley 
gives the number of revolutions of the pul¬ 
ley for each time the mark passes. The 
number of revolutions of the pulley to one 
of the belt can also be easily determined by 
slowly turning the pulley or pulling the belt 
until the latter makes one complete trip 
around, at the same time counting the revo¬ 
lutions of the pulley. If the machine has 
no belt, it can be supplied with one tem¬ 
porarily for the purpose of the test, a piece 

of tape with a knot or an ink mark being sufficient. Care should 
be taken in all these tests of speed with belts not to allow any 
slip; for example, in the case of the tape belt just referred to, 
this belt should pass around the pulley of the machine and some 
light wheel of wood or metal which turns so easily as not to cause 
any slip of the belt on the pulley of the machine. The belt should 
not have much elasticity like a rubber band, as it would give an 
incorrect result. 



v • 


Fig. 83. Hand Tachom¬ 
eter 

Courtesy of James G. 
Biddle 


TORQUE 

Prony Brake. Torque, or pull, is measured in the case of a 
motor by the use of a Prony or strap brake. The former consists of 
a lever L L of wood, clamped on the pulley of the machine to be 
tested, as indicated in Fig. 84. The pressure of the screws S S is 
then adjusted by the wing-nuts until the friction of the clamp on 
the pulley is sufficient to cause the motor to take a given current, 
and the speed is then noted. Usually, the maximum torque or pull 
is the most important to test; and this is obtained in the case of a 
constant-potential motor by tightening the screws S S until the 


323 



100 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

motor draws its full current, as indicated by an ammeter. The full¬ 
load current is usually marked on the name plate of the motor. If 
it is not known, the following formulas may be used: 



For d. c. motors: 

^ A h.p. x 746 

Current = - 

Volts x Efficiency . 

For single phase a. c. motors: 

r ,_ h.p. x 746 _ 

urren - y Q ^ g x pffi e i enC y x Power Factor 

For three-phase a.c. motors: 

p ,_ h.p. x 746 _ 

* urren “ y 0 its x Efficiency x Power Factor x 1.73 

For two-phase a. c. motors: 

p , _ h.p. x 746 _ 

urren - y Q ^. g x Effi e i enC y x Power Factor x 2 

The efficiency and the power factor in these formulas should 
always be expressed as decimals. When the rating is given in 
kw., instead of h. p., this rating multiplied by 1000 should be sub¬ 
stituted instead of h. p.x746. 

The torque or pull is measured by known weights or, more 
conveniently, by a spring balance P. If desired, the test may also 
be made at three-quarters, one-half, or any other fraction of the 
full-load current. 

The torque in foot-pounds, which should be obtained, can also 


324 


















MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 101 


be calculated from the power at which the machine is rated, by the 
formula: 


or 


Torque = 


h.p. x 33,000 
6.28 xS 


p_ h.p.x 33,000 
,2tt rxS 


in which h. p. is the horsepower of the machine at full load, and 8 
is the speed of the machine in revolutions per minute at full load.' 
Torque is given at unit radius, commonly pounds at one foot. The 
pull at any other radius is converted into torque by multiplying 
by the radius. One h.p. produced at a speed of 1000 revolutions 
requires a pull of 5.25 pounds at the end of a 1-foot lever; at 500 
revolutions, twice as much; at 2000 revolutions, half as much; and 
so on. If the lever is 4 feet, the pull is one-fourth as much, etc. 

Torque of a Generator. The torque of a generator, that is, 
the power required to drive it, is very conveniently determined by 
operating it as a motor and testing it by the friction brake, as 
described above, the torque of a generator being practically equal 
to that of a motor under similar conditions. 


POWER 

Electrical Power. The electrical power of a generator or 
motor is found by testing the voltage and the current at the ter¬ 
minals of the machine, as already described, and multiplying the 
two together, which gives the electrical power of the machine in 
watts.* Watts are converted into horsepower by dividing by 746, 
and into kilowatts by dividing by 1000. 

Mechanical Power. The mechanical power of a generator 
or motor, that is, the power required for or developed by it, is 
found by multiplying its pull by its speed and by the circumfer¬ 
ence on which the pull is measured, and dividing by 33,000. That is, 

TT PxSx6.28xR 

Horsepower = nnn - 


* In testing an alternating-current machine, a wattmeter should be employed 
instead of a voltmeter and an ammeter, as explained later. 


325 






102 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

in which P is the pull in pounds; 8 is the speed in revolutions per 
minute; and R is the radius in feet at which P is measured. 


Efficiency 


Analysis of Definition. The efficiency is determined in the 
case of a generator by dividing the electrical power generated by it 
by the mechanical power required to drive it; that is, 


Efficiency of generator = 


Electrical power 
Mechanical power 


The efficiency of a motor is the mechanical power developed 
by it, divided by the electrical power supplied to it; that is, 


Efficiency of motor = 


Mechanical power 
Electrical power 


Efficiency of D.C. Generators. Outline of Method. In test¬ 
ing the efficiency of d. c. generators there are several methods which 
can be followed. One large manufacturer has adopted the “ meas¬ 
urement of losses” method, and it is probably one of the best for 
machines of all sizes. In this method the following quantities are 
measured: 

Voltage of the line 
Current in the line 
Current in the shunt field 
Current in the armature 
Current in the series field 
Current in the series field shunt 
Resistance of the brush contact 

Resistance of the shunt field (hot) 

Resistance of the armature (hot) 

Resistance of the series field (hot) 

Resistance of the series field shunt (hot) 

Core loss 

Brush friction loss 
Bearing friction loss 

Core-Loss and Friction Test. These last three items are de¬ 
termined by a separate test in the following manner: Drive the 
generator by a small motor, say 10 per cent of the capacity of the 
generator. Belt drive is usually satisfactory but, if great accuracy 


326 





MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 103 


is necessary, the motor should be direct-connected to the generator. 
The motor should not have to carry more than 50 per cent of its 
full-load rating with maximum field strength on the generator. The 
motor should be run at its normal speed and field strength as nearly 
as possible. The resistance of the motor armature should be known. 
The field strength must be kept constant at about normal value. 
The speed of the motor can be varied by changing the voltage 
across its armature. The motor and the generator should be run 
for some time to allow all friction conditions to become constant. 
Readings should be obtained as follows: 

Input to the motor with all brushes down and no field on the generator. 

Input to the motor with all brushes raised and no field on the generator. 

(The difference in the above gives the loss in brush friction.) 

Input to the motor with various values of field current in the generator 
from zero up to such a value as will give voltage considerably above normal. 

Input to the motor while running free with the same field strength as 
used during the balance of the test. 

The speed must be held absolutely constant and no readings 
taken when the speed is changing in either direction. It is readily 
seen that by correcting the input to the motor to allow for the P R 
loss in the armature, and for the input to the motor with no field 
on the generator, we can get the core loss at the different field 
strengths. 

Final Efficiency. We can now add the PR losses in the 
different sections of the electric circuits to the core loss and the 
friction losses, and obtain the total loss in the generator. The 
total input then becomes: 


W^Wo+L 

P Wq W 0 

MV W 0 + L 

in which W 1 is watts input; W 0 is watts output; L is total loss in 
watts; and E is efficiency. 

These losses might have values somewhat as giVen below for a 
20 kw. generator: 



104 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


Core loss...about 3% 

Bearing friction and windage. ,.about 2*4% 

Brush friction ...about %% 

I-B losses.. about 2 to 4% 

This would mean an efficiency of about 91 or 92 per cent. The 
losses given above can be further divided, but such division is not 
usually necessary. It is to be noted that there are in practice 
additional losses called “load losses”, very difficult to measure. 
These are usually about 1 or 2 per cent. The method described 
above can be used for any direct-current machine. 

Efficiency of A. C. Generators. For a. c. machines a similar 
method is used, but in addition to the open-circuit core loss, the 
core loss is measured with the armature short-circuited and suffi¬ 
cient field to give normal armature current. The total losses 
obtained are added to the output to obtain the input the same as 
for d. c. machines, and the efficiencies are obtained in the same way. 

Efficiency of Motor- Generators and Converters. The effi¬ 
ciency of a motor-generator or ordinary converter is very easily 
determined by simply measuring the input and output in watts 
(by wattmeters or by ammeters and voltmeters for direct currents), 
and dividing the latter by the former. These electrical methods of 
testing are preferable to mechanical, for the reason that the volts 
and the amperes can be easily and accurately measured, and their 
product gives the power in watts.* Mechanical measurements of 
power by dynamometer or other means are more difficult, and not 
so accurate, but brake tests give, good practical results. 

Measurement of Power in A. C. Circuits 

In circuits carrying alternating currents' and having some 
inductive load either in the form of motors or arc lamps or a partly 
loaded transformer, etc., the ordinary method of determining the 
power, by voltmeter and ammeter measurements, is not applicable, 
as the current is seldom in phase with the e.m.f. and, therefore, 
the product volts x amperes is not the true power. 

Indicating Wattmeter Method. There are several means for 
determining the true power of an a. c. circuit, the simplest being 
an indicating wattmeter. A wattmeter is an electrodynamometer 

* When alternating-current machinery is being tested, use wattmeters. 


328 







' MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 105 

provided with two coils, a fixed one of coarse wire, the other mov¬ 
able and of fine wire. This movable coil is connected in series 
with a large nonindnctive resistance, so that the time constant of 
the fine-wire circuit is extremely small, and hence its impedance is 
practically equal to its resist¬ 
ance ; the current in, and the re¬ 
sulting field of, the fine-wire 
coil will under these conditions 
be practically in phase with the 
potential difference across its 
terminals. The field produced 
by the coarse-wire coil is di¬ 
rectly proportional to the cur¬ 
rent flowing through it at any 
instant. Hence, the couple act¬ 
ing on the fine-wire coil is proportional at a given instant to 
the product of these two fields; so that the reading of the instru¬ 
ment, which depends on the mean value of the couple, will be pro¬ 
portional to the mean power, and, by providing the instrument 
with the proper scale, it will read directly in watts. 

Single-Phase Circuit. In Fig. 85, A B represents an inductive 
load—say of a single-phase motor—of which the power input is to 



Fig. 85. Wiring Diagram for Determin¬ 
ing Input by Indicating Wattmeter 
Method in Single-Phase Circuit 



Fig. 86. Wiring Diagram for Testing Power Input in Two-Phase Circuit 

be determined; CD, the terminals of the thick-wire coil (current- 
coil) of the wattmeter; and EF, the voltage- or pressure-coil ter¬ 
minals. When connected as above indicated, the wattmeter in¬ 
dicates directly in watts the power supplied. 

Two-Phase Circuit. In the case of a two-phase system, where 


329 
















































106 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

the two circuits are independent, the power may be measured by 
placing a wattmeter in each phase, as shown in Fig. 85, and adding 
the two readings. If the motor be connected up as shown in 



Pig. 87. Power Input Diagram for Three-Phase Circuit, Star-Connected 


Fig. 86 ,* where A B forms a common return, the wattmeters are 
placed as indicated, care being taken to place the current-coils in 



w 


r 

— 1_ 


■- G 




(4-F 






Fig. 88. Power Input Diagram for Three-Phase Circuit, Delta-Connected 

the outside mains; and the power supplied is equal to.the sum of 
the two wattmeter readings. 

* This form of connection is possible only when the generator has two inde¬ 
pendent windings, one for each phase. 


330 




































MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 107 

Three-Phase Circuit. The power of a balanced or unbalanced 
three-phase system can be determined by the use of two wattmeters 
connected as shown in Figs. 87 and 88. The current-carrying 
coils are placed in series with two of the wires and the pressure 
coils, respectively, connected be¬ 
tween these two mains and the 
third wire. The algebraic sum of 
these two wattmeter readings 
gives the true power supplied. 

When the power factor of the 
system is less than .5, one of the 
wattmeters will read negatively. 

It is sometimes difficult to deter¬ 
mine whether the smaller readings 
are negative or not. If in doubt, 
give the wattmeter a separate load of incandescent lamps, and 
make the connections such that both instruments deflect positively; 
then reconnect them to the load to be measured. If the terminals 



Fig. 89. Power Input Diagram for a 
Four-Wire Three-Phase Circuit 
with One Wattmeter 



Fig. 90. Power Input Diagram for a Three-Phase Three-Wire Circuit with One 

Wattmeter 


of one instrument have to be reversed, the readings of that watt¬ 
meter are negative. 

Balanced Four-Wire Three-Phase Circuit. To measure the 
power of a balanced four-wire three-phase system, one wattmeter 


331 
















































108 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

may be connected as shown in Fig. 89, and the wattmeter reading 
multiplied hy 3. Usually, however, a four-wire three-phase system 
is unbalanced; and to determine the power supplied under this 
condition, three wattmeters should be employed, one for each phase 



the power supplied being equal to the algebraic sum of all three 
readings. 

It is obvious that in any of the above instances one watt¬ 
meter could be employed, provided the necessary switches are used. 
Assuming, for example, the three-phase three-wire case, one watt¬ 
meter would require switch connections as shown in Fig. 90. A 


332 





































































































































MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 109 

is a double-pole switch which, when thrown to the left, places the 
current coil of the wattmeter in series with the conductor of No. I, 
and, when thrown to the right, places it in series with No. III. 
Similarly, switch B changes the pressure terminals from between 
machines I and II to machines III and II; while switches C and D 
are short-circuiting switches. One of these switches is closed previous 
to removing the current coil from one phase to the other, and the 
other one is opened after the coil is in the position indicated in the 
diagram. 

In general practice, power in polyphase circuits is measured 
by polyphase wattmeters. Such an instrument is merely a com¬ 
bination of two or three single-phase instruments. Thus for two- 
phase non-interconnected systems, two single-phase elements are 
mounted together with the two moving elements mounted on the 
same shaft and carrying one pointer. Thus the movement of 
the pointer is caused by the combined torque of the two elements 
and tfie indication on the scale is equal to the algebraic sum of 
the two. 

Three elements could be combined in the same way for three- 
phase four-wire circuits. In practice a third current element is 
customarily added to the usual two of a three-wire instrument. 
This third coil is divided, each half of it being placed so as to act 
with one of the two potential coils. This arrangement does not give 
an absolutely correct indication, but the error is so small that it 
does not throw the indications outside the limits of commercial 
accuracy. 

Instrument Transformers. In a great many cases in modern 
practice it is necessary to use instrument transformers. Where 
the current involved is more than 200 or 300 amperes, or in some 
cases even less, the instruments can not be made to carry the full 
amount and current transformers are used to step the current 
down. The secondary current is usually 5 amperes. Where the 
voltage is more than 1100, both current and potential transformers 
are usually used, even for small currents, since it is not safe to 
bring high voltage directly into the instrument. Fig. 91 shows 
the wiring diagram of a standard central station switchboard in 
which the instruments are operated from current and potential 
transformers. 


333 





110 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

LOCALIZATION AND REMEDY OF TROUBLES 

General Plan. The promptness and ease with which any 
accident or difficulty with electrical machinery can be dealt with 
will always have much to do with the success of a plant. A list of 
troubles, symptoms, and remedies for the various types and sizes 
of dynamos and motors in common use has been prepared to facili¬ 
tate the detection and elimination of such difficulties. 

It is evident that the subject is somewhat complicated and diffi¬ 
cult to handle in a general way, since so much depends upon the 
particular conditions in any given case, every one of which must 
be included in the “Table of Troubles” in such a way as to dis¬ 
tinguish it from all the others. Nevertheless, it is remarkable how 
much can be covered by a systematic statement of the matter, and 
nearly all cases of trouble most likely to occur are covered by the 
table, so that the detection and remedy of the defect will result from 
a proper application of the rules given. 

It frequently happens that a trifling oversight, such as allow¬ 
ing a wire to slip out of a terminal, will cause as much annoyance 
and delay in the use of electrical machinery as the most serious acci¬ 
dent. Other troubles, equally simple but not so easily detected, are 
of frequent occurrence. 

The rules are made, as far as possible, self-explanatory; but a 
statement of the general plan followed in its most important fea¬ 
tures will facilitate the understanding and use of the table. 


USE OF TABLE OF TROUBLES 

In the use of the Table of Troubles the principal object should 
be to separate clearly the various causes and effects from one 
another. A careful and thorough examination should first be made; 
and, as far as possible, one should be perfectly sure of the facts, 
rather than attempt to guess what they are and jump at conclu¬ 
sions. Of course, one should take general precautions and pre¬ 
ventive measures before any troubles occur, if possible, rather than 
wait until a difficulty has arisen. For example, one should see 
that the machine is not overloaded or running at too high voltage, 
and should make sure that there is oil in the bearings. Neglect 


334 




MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 111 

and carelessness with any machine are usually and deservedly fol¬ 
lowed by accidents of some sort. It is usually wise to stop the 
machine, if possible, when any trouble manifests itself, even though 
it does not seem to be very serious. It is often practically impos¬ 
sible to shut down altogether; therefore spare apparatus should 
always be ready. The continued use of defective machinery is a 
common but very objectionable practice. 

Classification of Troubles. The general plan of the table is 
to divide all troubles that may occur to generators or motors into 
ten classes, the headings of which are the ten most important and 
obvious bad effects produced in these machines, viz: 


Table of Troubles 


I. 

II. 

III. 

IV. 

y. 

VI. 

VII. 

VIII. 

IX. 

X. 


Sparking at Commutator 

Heating of Commutator and Brushes 

Heating of Armature 

Heating of Field Magnets 

Heating of Bearings 

Noisy Operation 

Speed Not Right 

Motor Stops or Fails to Start 

Dynamo Fails to Generate 

Voltage Not Right 


Any one of these general effects is evident, even to the casual 
observer, and still more so to any person making a careful exami¬ 
nation; hence nine-tenths of the possible cases can be eliminated 
immediately. 

The next step is to find out which particular one of the eight 
or ten causes in this class is responsible for the trouble. This 
requires more careful examination, but nevertheless can be done 
with comparative ease in most cases. One cause may produce two 
effects, and, vice versa , one effect may be produced by two causes; 
but the table is arranged to cover this fact as far as possible. In 


a complicated or difficult case, it is well to read through the entire 
table and note what causes can possibly apply. ' Generally, there 
will not be more than two or three; and the particular one can be 
picked out by following the directions, which show how each case 
may be distinguished from any other. 


335 




112 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


I. SPARKING AT COMMUTATOR 

This is one of the most common of troubles, being often quite 
serious because it burns and cuts the commutator and brushes, at 
the same time producing heat that may spread to and injure the 
armature or bearings. Any machine having a commutator, in¬ 
cluding practically all direct-current and some alternating-current 
machines, is liable to have this trouble. * The latter usually have con¬ 
tinuous collecting rings not likely to spark; but self-exciting or 
composite-wound alternators, rotary converters, and some alter¬ 
nating-current motors have supplementary direct-current commu¬ 
tators. A certain amount of sparking occurs normally in most 
constant-current dynamos for arc lighting, where it is not very 
objectionable, since the machines are designed to stand it and the 
current is small. 

Cause 1. Armature carrying too much current. This is due 

to (a) overload (for example, too many lamps, motors, etc., fed by 
generator, or too much mechanical work done by motor; a short 
circuit, or ground on the line, may also have the effect of over¬ 
loading a generator) ; (b) excessive voltage on a constant-potential 
circuit, (or excessive amperes on a constant-current circuit). In the 
case of a motor, any friction, such as armature striking pole 
pieces, or shaft not turning freely, may have the same effect as 
overload. 

Symptom. Whole armature becomes overheated, and belt (if 
any) becomes very tight on tension side, sometimes squeaking be¬ 
cause of slipping on pulley. Overload due to friction is detected 
by stopping the machine, and then turning it slowly. (See V 
and YI, 2.) 

Remedy, (a) Reduce the load, or eliminate the short circuit 
or ground on the line; (b) decrease size of driving pulley; or (c) 
increase size of driven pulley; (d) decrease magnetic strength of 
field in the case of a generator, or increase it in the case of a motor. 
If excess of current can not satisfactorily be overcome in any of 
the above ways, it will be necessary to change the machine or its 
winding. Overload due to friction is eliminated as described under 
Y and YI, 2. 


336 


MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 113 

If the starting or regulating rheostat of a motor has too little 
resistance it will cause the motor to start‘too suddenly and to 
spark badly at first. The only remedy is more resistance. 

Cause 2. Brushes not set at proper commutating point. 

Symptom. Sparking at the brushes. 

Remedy. Brushes should be carefully set on the proper neu¬ 
tral point on the commutator. For non-commutating-pole ma¬ 
chines this is either ahead of or behind (depending whether the 
machine is a generator or a motor) a radial line on the commutator 
usually passing through the center of the pole piece. This point 
is found by shifting the brushes from the geometrical or “mechan¬ 
ical” neutral so that at no load and normal voltage a slight spark, 
the size of a pin point, shows at the edge of the brush. This point 
will usually be the proper full-load running position of the brushes. 
While the usual position of the brushes is about opposite the cen¬ 
ter of the pole piece, in some machines it may be opposite the space 
between adjacent pole pieces, depending on the winding of the 
armature. If the brushes are set exactly wrong, this will cause a 
generator to fail to generate, and a motor to fail to start, and will 
blow the fuse or open the breaker in the latter case. (See IX, 6.) 

The proper brush position for commutating-pole generators 
coincides very closely with the mechanical neutral, and is best de¬ 
termined thus: Remove one brush from a brush holder and in its 
place insert a fiber brush of similar dimensions. Through this 
drill two holes, about the size of the lead in a pencil, at such a 
distance apart that the holes are respectively over the centers of two 
adjacent commutator-bars. Insert in these holes the lead from a 
pencil so that the ends of the lead ride lightly on the commutator. 
To the outer ends connect a low-reading voltmeter, and with normal 
voltage on the generator move the brush-holder yoke until the volt¬ 
meter shows a zero reading. This will be the correct brush position, 
or ‘ ‘ electrical neutral ’ \ 

In the case of a commutating-pole motor, the electrical neutral 
is determined by shifting the brushes until the same speed is 
obtained in either direction, with equal value of field current and 
equal values of voltage. 

In the case of all d.c. generators and motors it is of prime 
importance that the brushes be placed parallel to the commutator- 


337 


114 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


bars, and the various sets of brushes spaced exactly the same 
distance apart. 

Cause 3. Commutator rough, eccentric. The commutator 

may be rough or eccentric; may have one or more high bars project¬ 
ing above the others; one or more low bars , or projecting mica: 
or may have as many low black spots on the commutator as there 
are pairs of poles on the machine. Any one of these may cause 
the brushes to vibrate or to be actually thrown out of contact with 
the commutator. 

Symptom. Note whether there is a glaze or polish on the com¬ 
mutator which shows smooth operation; touch the revolving com¬ 
mutator with the point of a pencil and any roughness or low or 
high spots can be detected. In the case of an eccentric commutator 
careful examination shows a rise or fall of the brushes when the 
commutator turns slowly, or a chattering of the brush when it is 
running fast. 

Remedy. First, go all over the armature, commutator, and 
equalizer connections, and test for high resistance joints. If any 
are found they should at once be soldered. (This applies also to 
rotary converters.) The proper brush setting and spacing should 
be checked, also the air gap and magnetic joints on the machine. 
If the commutator is not in very bad shape it may be ground down 
with a piece of fine sandstone, or sand or carborundum paper (not 
emery). This should be fitted to a wood block cut to the same 
curvature as the commutator. 

If the commutator is in very bad shape or is eccentric, the 
armature should be taken out and put in a lathe and the commu¬ 
tator turned. Large machines are fitted with a slide rest attach¬ 
ment for turning the commutator without removing it. 

For turning the commutator, a diamond point tool should 
be used. Only a fine cut should be taken off each time in order 
to avoid catching in, or chattering on, the copper bars, which are 
very tough. The surface is then finished with either a sandstone 
or fine sandpaper. 

In order that the commutator may wear smooth and work 
well, the armature shaft should move freely back and forth about 
i or A of an inch in its bearings while running. 

A commutator should have a glaze of a brown color. A very 


338 


MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 115 


bright or scraped appearance does not indicate the best condition. 
A light grade of engine oil used sparingly on the commutator is 
beneficial. 


Cause 4. Brushes make poor contact with commutator. 

Symptom. Close examination shows that brushes touch only 
at one corner, or only in front or behind, or there is dirt on surface 
of contact. Sometimes, owing to the presence of too much oil or 
from other cause, the brushes and commutator become very dirty, 
and covered with smut. They should then be carefully cleaned 
by wiping with oily rag or benzine, or by other means. 

Occasionally a “glass-hard” carbon brush is met with. It is 
incapable of wearing to a good seat or contact, and will touch at 
only one or two points. Some carbon brushes are of abnormally 
high resistance, so that they do 
not make good contact. In such 
cases new brushes should be sub¬ 
stituted. 

Remedy. Carefully fit, ad¬ 
just, or clean brushes until they 
rest evenly on the commutator, 
with considerable surface of con¬ 
tact and with sure but not too 
heavy pressure. Copper brushes require a regular brush jig, Fig. 
92. Carbon brushes can be fitted perfectly by drawing a strip of 
sandpaper back and forth between them and the commutator while 
they are pressing down. A band of sandpaper may be pasted or tied 
around the commutator, and the armature then slowly revolved by 
hand or by power while the brushes are pressed upon it. 

Cause 5. Short-circuited or reversed coil or coils in arma¬ 
ture. 

Symptom. A motor will draw excessive current, even when 
running free without load. A generator will require considerable 
power, even without any load. For reversed coil, see III, 5. 

The short-circuited coil is heated much more than the others, 
and is liable to be burnt out entirely; therefore the machine should 
be stopped immediately. If necessary to run machine in order to 
locate the trouble, one or two minutes is long enough; but this may 



Fig. 92. Typical Jig for Carbon Brushes 


339 



116 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

be repeated until the short-circuited coil is found by feeling the 
armature all over. 

An iron screw driver or other tool held between the poles 
near the revolving armature vibrates very perceptibly as the 
short-circuited coil passes. Almost any armature will cause a slight 
but rapid vibration of a piece of iron held near it; but a short 
circuit produces a much stronger effect only once per revolution. 
Care should be taken not to let the piece of iron be drawn in and 
jam the armature. 

The current pulsates and torque is unequal at different parts 
of a revolution, these symptoms being particularly noticeable when 
several coils are short-circuited or reversed, and the armature is 
slowly turned. If a large portion of the armature is short-cir¬ 
cuited, the heating is distributed and is harder to locate. In this 
case a motor runs very slowly, giving little power but having full 
field magnetism. A short-circuited coil can also be detected by the 
drop-of-potential method. For generators, see IX, 3. 

Remedy . A short circuit is often caused by a piece of solder, 
copper, or other metal getting between the commutator-bars or their 
connections with the armature; and sometimes the insulation be¬ 
tween or at the ends of these bars is bridged over by a particle of 
metal. In any such case the trouble is easily found and corrected. 
If, however, the short circuit is in the coil itself, the only effective 
remedy is to rewind the coil. 

One or more “grounds” in the armature may produce effects 
similar to those arising from a short circuit. (See Cause 7.) 

Cause 6. Broken circuit in armature. 

Symptom. Commutator flashes violently while running, and 
commutator-bar nearest the break is badly burnt; but in this case 
no particular armature coil will be heated as in the last case; and 
the flashing will be very much worse, even when turning slowly. 
This trouble, which might be confounded with a bad case of “high 
bar” in commutator (Cause 3), is distinguished therefrom by 
slowly turning the armature, when violent flashing will continue 
if circuit is broken; but not with high bar unless it is very bad, 
in which case it is easily felt or seen. A very bad contact has 
almost the same effect as a break in the circuit. 

Remedy. A break or bad contact can be located by the 


340 


MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 117 

“drop” method (p. 88) or by a continuity test (p. 93). The 
trouble is often found where the armature wires connect with the 
commutator, and not in the coil itself; the break may be repaired 
or the loose wire fastened or reconnected. If the trouble is due 
to a broken commutator connection and can not be fixed, the dis¬ 
connected bar may be temporarily connected to the next by solder. 
If the break is in the coil itself, rewinding is generally the only 
cure. The trouble may be remedied temporarily by connecting to¬ 
gether by wire or solder the two commutator-bars or coil-terminals 
between which the break exists. It is only in an emergency that 
armature coils should be cut out or commutator-bars connected 
together, or other makeshifts resorted to; but it sometimes avoids 
a very undesirable shut-down. A very rough but quick and simple 
way to connect two commutator-bars is to hammer or otherwise 
force the coppers together across the mica insulation at the end of 
the commutator. This should be avoided if possible; but if it has 
to be done in an emergency, the crushed material can afterwards 
be picked out and the injury smoothed over. In carrying out any 
of these methods, great care should be taken not to short-circuit 
any other armature coil, which would cause sparking (Cause 5). 

Cause 7. Ground in armature. 

Symptom. Two “grounds” (accidental connections between 
the conductors on the armature and its iron core or the shaft or 
spider) would have practically the same effect as a short circuit 
(Cause 5), and would be treated in the same way. A single ground 
would have little or no effect, provided the circuit is not intention¬ 
ally or accidentally grounded at some other point. On an electric¬ 
railway (“trolley”) or other circuit employing the earth as a 
return conductor, one or more grounds in the armature would 
allow the current to pass directly through them, and would cause 
the motor to spark and have a variable torque at different parts of 
a revolution. 

Remedy. A ground can be detected by testing with a mag- 
neto bell (p. 92). It can also be located by the drop-of-potential 
method (p. 88). Another way to locate it is to wrap a wire 
around the commutator so as to make connection with all of the 
bars, and then connect a source of current to this wire and to the 
armature core (by pressing a wire upon the latter). The cur- 


341 


118 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


rent will then flow from the armature conductors through the 
ground connection to the core, and the magnetic effect of the arma¬ 
ture winding will be localized at the point where the ground is. 
This point is then found by the indications of a compass needle 
when slowly moved around the surface of the armature. The cur¬ 
rent may be obtained from a storage battery or from the circuit, 
but should be regulated by lamps or other resistance so as not 
to exceed the normal armature current. Sometimes the ground 
may be in a place where it can be corrected without much trouble, 
but usually the particular coil and often others must be rewound. 

Cause 8. Weak field magnetism. 

Symptom. Pole pieces not strongly magnetic when tested with 
a piece of iron. Point of least sparking shifted considerably from 
normal position owing to relatively strong distorting effect of arma¬ 
ture magnetism. Speed of a shunt motor high.* A generator fails 
to generate the full e. m. f. or current. 

If one field coil is reversed and opposed to the others, it will 
weaken the field magnetism and cause bad sparking. This may 
be detected by examining the field coils to see if they are all con¬ 
nected in the right way, or by testing with a compass needle. (See 
IX, 4.) The series-coil of a compound-wound generator or motor is 
often connected wrongly, and will have an opposing effect; that is, 
will reduce the voltage of the former or raise the speed of the 
latter with increase of load. 

Remedy. A break, short circuit, or ground, if external and 
therefore accessible,' is easily repaired. If not accessible, the only 
remedy is to rewind or replace the faulty coil. A shunt motor 
will show dangerous sparking if the armature is connected before 
the field, in starting. In this case the starting-box connections 
should be changed so that the field is connected before the armature. 

If the voltage is too low on a circuit, it may cause sparking 
in a shunt motor; and if the voltage cannot be raised, the resistance 
of the field circuit should be reduced by unwinding a few layers 
of wire or by substituting other coils. (See VII, VIII, IX, and X.) 

* Under some circumstances a shunt motor with a very weak field, or with 
no field, will Vun slow, stop, or run backward. The usual and safest assumption is 
that the speed will increase as the field is weakened, and that with no field the motor 
may attain such a speed that it will destroy itself. Never, under any circumstances, 
should the field circuit he opened when voltage is applied to the terminals. 


342 



MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 119 

Cause 9. Vibration of machine. 

Symptom. Considerable vibration is felt when the hand is 
placed upon the machine, and sparking decreases if the vibration 
is reduced. 

Remedy. The vibration is usually due to an imperfectly bal¬ 
anced armature or pulley (see VI, 1), to a bad belt (see VI, 6), 
or to unsteady foundations; and the remedies described for these 
troubles should be applied. 

Any considerable vibration is likely to produce sparking, of 
which it is a common cause. This sparking can be reduced by 
increasing the pressure of the brushes on the commutator, but 
the vibration itself should be overcome. 

Cause 10. Chatter of brushes. The commutator sometimes 
becomes sticky when carbon brushes are used, causing friction, 
which throws the brushes into rapid vibration as the commutator 
revolves, similar to the action of a violin bow. 

Symptom. Slight tingling or jarring is felt in brushes. 

Remedy. Clean commutator, and oil slightly. 

Cause 11. Flying break in armature conductor. 

Symptom. No break found by test with armature standing 
still, but break shown by flashing at brushes when running, being 
usually due to centrifugal force. 

Remedy. Tighten connections to commutator, or repair broken 
wire, etc. 

II TO V. EXCESSIVE HEATING IN GENERATOR OR MOTOR 

General Instructions. The degree of heat that is injurious 
or objectionable in a generator or motor is determined, as a rough 
test, by feeling the parts. If the heat is bearable to the hand, it is 
entirely harmless; but if unbearable, the safe limit of temperature 
has been approached or passed, and the heat should be reduced 
in some of the ways that are indicated below. In testing with 
the hand, allowance should be made for the fact that bare metal 
feels much hotter than cotton at the same temperature. The back 
of the hand is more sensitive than the palm for this test. If the 
heat has become so great as to produce an odor or smoke, the safe 
limit has been far exceeded, and the current should be shut off 


343 


120 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

immediately and the machine stopped, as this indicates a serious 
trouble, such as a short-circuited coil or tight hearing. The ma¬ 
chine should not again be started until the cause of the trouble 
has been found and positively overcome. Of course, neither water 
nor ice should ever be used to cool electrical machinery, except 
possibly the bearings of large machines at points where they can 
be applied without danger of wetting the other parts. 

Feeling for heat will serve as a rough test to detect excessive 
temperatures or in emergencies; but, of course, the sensitiveness 
of the hand varies, and it makes a great difference whether the 
surface is a good or bad conductor of heat. The proper and reli¬ 
able methods for determining rise in temperature in an operating 
machine are given on page 75. 

It is very important, in all cases of heating, to locate the 
source of heat in the exact part in which it is produced. It is a 
common mistake to suppose that any part of the machine that is 
found to be hot is the seat of the trouble. A hot bearing may 
cause the armature or commutator to heat, or vice versa. In every 
case all parts of the machine should be tried to find which is the 
hottest, since heat generated in one part is rapidly diffused through¬ 
out the machine. It is better to make observations for heating by 
starting the whole machine when cool, which is done by letting it 
stand for several hours. 

II. Heating of Commutator and Brushes 

Cause 1. Heat spread from another part of machine. 

Symptom. Start with the machine cool, and run for a short 
time, so that heat will not have time to spread. The real seat of 
trouble is the part that heats first. 

Remedy. See III, IY, and Y. 

Cause 2. Sparking. Any of the causes of sparking will 
cause heating, which may be slight or serious. 

Symptom and Remedy. See I. 

Cause 3. Tendency to spark, or slight sparking hardly visi¬ 
ble. Sometimes before sparking appears, serious heating is pro¬ 
duced by the causes of sparking, such as the short-circuiting of 
the coils as their commutator bars pass under the brushes. 

Symptom. Fine sparks may be found by sighting in exact 


344 


MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 121 

line with the surface of contact between the commutator and 
brushes. 

Remedy. Reduced by applying the principal remedies for 
sparking, such as slightly shifting rocker-arm. (See “Sparking at 
Commutator”, I.) Apply the remedies with extra care. This incip¬ 
ient sparking may be due to incorrect design, which can be corrected 
only by reconstruction; for example, it may be due to insuffi¬ 
cient field strength, and this can be cured by increasing the ampere 
turns of field winding. 

Cause 4. Overheated commutator will decompose carbon 
brush. The effect is to cover commutator with a black film, 
which offers resistance and aggravates the heat. 

Symptom. Commutator covered with dark coating; commu¬ 
tator, brushes, and holders show marks of abnormal heat. 

Remedy. Commutator and brushes should be carefully 
cleaned, and the latter adjusted to make good contact at the 
proper points. 

Cause 5. Bad connections in brush holder, cable, etc. 

Symptom. Holder, cable, etc., feel hottest; abnormal resistance 
found in these parts by “drop” method. 

Remedy. Improve the connections. 

Cause 6. Arcing or short circuit in commutator. This may 
occur across mica or insulation between bars or other parts. 

Symptom. Burnt spot between parts; spark appears in the 
insulation when current is put on. 

Remedy. Pick out the charred particles; take commutator 
apart and repair; or put on new commutator. 

Cause 7. Carbon brushes heated by current. 

Symptom. Brushes hotter than other parts. 

Remedy. Use carbon of higher conductivity. Let the brush- 
holder grip brush closer to commutator, so as to reduce the length 
of brush through which the current must pass. Use larger brushes 
or a greater number. 

III. Heating of Armature 

Cause 1. Excessive current in armature coils. 

Symptom and Remedy. Symptom and Remedy the same as 
in case of I, Cause 1. 


345 


122 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

Cause 2. Short-circuited armature coils. 

Symptom and Remedy. Symptom and Remedy the same as 
in case of I, Cause 5. See also Cause 7. 

Cause 3. Moisture in armature coils. 

Symptom. The detection of moisture in armature coils is a 
difficult matter without measuring the insulation resistance. Some¬ 
times a careful inspection of the armature may reveal the presence 
of moisture, but on large machines the safest method is to apply 
an insulation test. 

Remedy. When the insulation test reveals the presence of 
moisture, the armature, if small, may be baked in an oven suffi¬ 
ciently warm to expel all moisture, but not hot enough to injure the 
insulation. If the armature is large it can not readily be removed 
and placed in an oven. The machine may then be connected to 
run as a generator or motor, at reduced voltage, in order not to 
break down the insulation which is weakened by the moisture 
present, the voltage being gradually brought up as the insulation 
increases. If more convenient, a current controlled by resistance 
or otherwise at, say, half of rated value may be sent through a 
moist armature or field winding to dry it out. 

Cause 4. Foucault currents in armature core. 

Symptom. Iron of armature core hotter than coils after a 
short run, and considerable power required to run armature when 
field is magnetized and there is no load on armature. This can be 
distinguished from Cause 2 by absence of sparking and absence 
of excessive heat in a particular coil or coils after a short run. 
(See “Stray Power Tests”.) 

Remedy. Armature core should be laminated more perfectly, 
which is a matter of first construction. 

Cause 5. One or more reversed coils on one side of arma¬ 
ture. This will cause a local current to circulate around arma¬ 
ture. 

Symptom. Excessive current when running free, but no par¬ 
ticular coil heated more than others. If a moderate current is 
applied to each coil in succession by touching wires carrying cur¬ 
rent to each pair of adjacent commutator-bars, a compass needle 
held over the coils will behave differently when the reversed coil is 


346 


MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 123 

reached. In a motor, the half of armature containing the reversed 
coils is heated more than the others. 

Note.—A ny excess of current taken by an armature when running free 
as a motor, whatever the cause, must be converted into heat by some defect in 
the machine; hence the ‘ 1 free current ’ ’ is the simplest and most complete test of 
efficiency and perfect condition. 

Remedy. Reconnect the coil to agree with the others. 

Cause 6. Heat conveyed from other parts. 

Symptom. Other parts hotter than armature. Start with 
machine cool, and see if other parts heat first. 

Remedy. See II, IV, and Y. 

Cause 7. Flying cross in armature conductor. 

Symptom and Remedy. Symptom and Remedy similar to the 
case of sparking (I, Cause 11), except that reference here is to the 
insulation of the conductors. 


IV. Heating of Field Magnets 

Cause 1. Excessive current in field circuit. 

Symptom. Field coils too hot to keep the hand on. Their 
temperature more than 50 degrees centigrade above that of room 
by resistance test or by thermometer. 

Remedy. In the case of a shunt-wound machine, decrease the 
voltage at terminals of field coils; or increase the resistance in field 
circuit by winding on more wire or putting resistance in series. 
In the case of a series-wound machine, shunt a portion of, or other¬ 
wise decrease, the current passing through field; or take a layer 
or more of wire off the field coils; or rewind with coarser wire. 
This trouble might be due to a short circuit in field coils in the 
case of a shunt-wound dynamo or motor, and would be indicated 
by the pole piece with the short-circuited coil being weaker than 
the others. This coil is cooler than the others; in fact, if completely 
short-circuited, it is not heated at all. This condition can be rem¬ 
edied only by rewinding the short-circuited coil. Measure resistance 
of the field coils to see if they are nearly equal. (See “Drop 
Method”, p. 88.) If the difference is considerable (say, more than 
5 or 10 per cent) it is almost a sure sign that one coil is short- 
circuited or double-grounded. 


347 


124 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

Cause 2. Foucault currents in pole pieces or field cores. 

Symptom. The pole pieces hotter than the coils after a short 
run. When making the comparison, it is necessary to keep the 
hand on the coils some time before the full effect is reached, because 
the coils are insulated and the pole pieces are bare metal, and even 
then the coils will not feel so hot, although their actual tempera¬ 
ture may be higher, if measured by a thermometer. 

Remedy. This trouble is due to faulty design of toothed-arma- 
ture machines, which can be corrected only by rebuilding, or is 
caused by fluctuations in the current. The latter can be detected, 
if the variations are not too rapid, by putting an ammeter in 
circuit; or rapid variations may be. felt by holding a piece of iron 
near the pole pieces and noting whether it vibrates. 

Cause 3. Moisture in field coils. 

Symptoms. The field circuit tests lower in resistance than nor¬ 
mal in that type of machine; and in the case of shunt-wound ma¬ 
chines the field takes more than the ordinary current. Field coils 
steam when hot, or feel moist to the hand. The insulation re¬ 
sistance also tests low. 

Remedy. Remove and bake field coils as in the case of small 
armatures. On large machines the field coils may be connected 
in parallel-series groups so as to get approximately one-half nor¬ 
mal current at reduced voltage. As the insulation resistance rises, 
the current may be brought up to normal value. (See “Heating of 
Armature”, III, 3.) 


V. Heating of Bearings 

The cause should be found and removed promptly, but heating 
of the bearings can be reduced temporarily by applying cold water 
or ice to them. This is allowable only when absolutely neces¬ 
sary to keep running; and great care should be taken not to allow 
any water to get upon the commutator, armature, or field-coils, as 
it might short-circ.uit or ground them. If the bearing is very hot, 
the shaft should be kept revolving slowly while the bearing is 
flushed with fresh oil, as it might “freeze”, or stick fast, if stopped 
entirely. 

Cause 1. Lack of oil. 

Symptom. Oil reservoir empty. Self-oiling ritigs fail to turn 


348 


MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 125 

with shaft. Shaft and bearing look dry, and often there is an 
odor of hot oil. 

Remedy. Loosen bearing cap screws and then retighten them 
with fingers only. This will give the bearings a little clearance. 
Open the drain cock on the side of the bearing and ponr fresh 
oil in top of bearing, allowing the oil to run through the bearing 
until temperature is reduced to a safe value. 

Cause 2. Grit or other foreign matter in bearings. 

Symptom. Best detected by removing shaft or bearings and 
examining both. Any grit can, of course, be felt easily, and will 
also cut the shaft. 

Remedy. Remove shaft or bearing, clean both very carefully, 
and see that no grit can get in. The oil should be perfectly clean; 
if it is not, it should be filtered. 

Cause 3. Shaft rough or cut. 

Symptom. Shaft will show grooves or roughness and will 
probably revolve stiffly. 

Remedy. Turn shaft in lathe; or smooth with fine file; and 
see that bearing is smooth and fits shaft. 

Cause 4. Bearings fit too tight. 

Symptom . Shaft hard to revolve. Hot spots develop in 
bearing. 

Remedy. Remove the bearing and scrape the spots that show 
wear; then coat the shaft with a thin layer of red lead and place 
the bearing on the shaft. Move the bearing back and forth and 
when it is removed the high spots will be covered with the red 
lead. These should be scraped off, and the process repeated until 
a snug-fitting bearing is obtained. 

Cause 5. Shaft “sprung” or bent. 

Symptom. Shaft hard to revolve, and usually sticks much 
more in one part of revolution than in another. 

Remedy. It is very difficult to straighten a bent shaft. It 
might be bent back or turned true, but probably a new shaft will 
be necessary. 

Cause 6. Bearings out of line. 

Symptom. Shaft hard to revolve, but is much relieved by 
slightly loosening the screws that hold the bearings in place, when, 
machine is not running and when belt, if any, is taken off. 


349 


126 MANAGEMENT 01 DYNAMO-ELECTRIC MACHINERY 


Remedy. Loosen the bearings by partly unscrewing bolts or 
screws holding them in place, and find their easy and true position, 
which may require one of them to be moved either sideways or up 
or down; then ream the holes of that bearing, or raise or lower it, 
as may be necessary, to make it occupy the right position when the 
screws are tightened. The armature, however, must be kept in 
the center of the space between the pole pieces, so that the clear¬ 
ance is uniform all around. (See Cause 9.) 

Cause 7. Thrust or pressure of pulley, collar, or shoulder on 
shaft against one or both of the bearings. 

Symptom. Move shaft back and forth with a stick applied 
to the end while revolving, and note if the collar or shoulder tends 
to be pushed or drawn against either bearing. It is usually desir¬ 
able that a shaft should move freely back and forth about an eighth 
of an inch, to make commutator and bearings wear smoothly. 

Remedy. Line up the belt; shift collar or pulley; turn off 
shoulder *on shaft, or file off bearing, until the shoulder does not 
touch when running, or until pressure is relieved. 

Cause 8. Too great a load or strain on the belt. 

Symptom. Great tension on belt. In this case the pulley 
bearing will probably be very much hotter 
than the other, and also worn elliptical, as 
indicated in Fig. 93, in which case the shaft 
can be shaken in the bearing in the direction 
of the belt pull, when the belt is off, provided 
the machine has been running long enough to 
wear the bearings. 

Remedy. Reduce load or tension, or use 
larger pulleys and lighter belt, so as to relieve 
side strain on shaft. (See “ Belting ’ ’, p. 7.) 

Cause 9. Armature off of center, producing much greater 
magnetic pull toward nearer side. 

Symptom. Heating of bearing on side where air gap is 
smallest. Poor commutation due to unequal air gap. 

Remedy. The fault is due either to some inherent defect in 
the machine, to the faces of the poles not being concentric with 
the armature, to faulty erection of the machine, or to wear on the 
bearings. 



Fig. 93. Diagram Showing 
Elliptical Bearing Due 
to Wear 


350 








MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 127 


In most cases this trouble can be remedied by raising or low¬ 
ering either the bearing pedestals or the magnet frame feet, by 
means of their sheet-iron shims, to obtain the proper air gap verti¬ 
cally. To obtain the correct air gap in a horizontal direction, there 
is usually enough play in the foundation bolt holes in large ma¬ 
chines. On small machines the proper adjustment is usually made 
by the manufacturer. If the bearings have worn very much it is, 
of course, advisable to re-babbitt them to restore the correct air 
gap between armature and fields. 


VI. NOISY. OPERATION 

Cause 1. Vibration due to armature or pulley being out of 
balance. 

Symptom. Strong vibration felt when the hand is placed 
upon the machine while it is running. Vibration changes greatly 
if speed is changed, and sometimes almost disappears at certain 
speeds. 

Remedy. Armature or pulley must be perfectly balanced by 
securely attaching lead or other weights on the light side, or by 
drilling or filing away some of 
the metal on the heavy side. The 
easiest method of finding in 
which direction the armature is 
out of balance is to take it out, 
and to rest the shaft on two 
parallel and horizontal A-shaped Fig * 94 - ^Proper Balance Armature 
metallic tracks sufficiently far 

apart to allow the armature to go between them, Fig. 94. If the 
armature is then slowly rolled back and forth, the heavy side will 
tend to turn downward. The armature and pulley should always be 
balanced separately. An excess of weight on one side of the pulley 
and an equal excess of weight on the opposite side of the armature 
will not produce a balance while running, though it does when 
standing still; on the contrary, it will give the shaft a strong 
tendency to “wobble”. A perfect balance is obtained only when 
the weights are directly opposite, i.e., in the same line perpen¬ 
dicular to the shaft. 



351 








128 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

Cause 2. Armature strikes or rubs against pole pieces. 

Symptom. Easily detected by placing the ear near the pole 
pieces; or by examining armature to see if its surface is abraded 
at any point; or by examining each part of the space between 
armature and field as armature is slowly revolved, to see if any 
portion of it touches, or is so close as to be likely to touch, when 
the machine is running. In small machines, the armature may be 
turned by hand to find out whether it sticks at any point. 

Remedy. See V, 9. 

Cause 3. Shaft collar or shoulder, hub or edge of pulley, or 
belt, strikes or scrapes against bearings. 

Symptom. Rattling noise, which stops when the shaft or pul¬ 
ley is pushed lengthwise away from one or the other of the bear¬ 
ings. (See Y, Cause 7.) 

Remedy . Shift the collar or pulley, turn off the shoulder 
on the shaft, file or turn off the bearing, move the pulley on 
the shaft, or straighten the belt, until there is no more striking, 
and the noise ceases. 

Cause 4. Rattling due to looseness of screws or other parts. 

Symptom. Close examination of the bearings, shaft, pulley, 
screws, nuts, terminals, etc., or touching the machine while run¬ 
ning, or shaking its parts while standing still, shows that some 
parts are loose. 

Remedy. Tighten up the loose parts, and be careful to keep 
them all properly set up. It is easy to guard against the occur¬ 
rence of this trouble, which is very common, by simply examining 
the various screws and other parts each day before the machine is 
started. Electrical machinery being usually high speed, the parts 
are particularly liable to shake loose. A worn or poorly fitted 
bearing might allow the shaft to rattle and make a noise, in which 
case the bearing should be refitted or renewed. 

Cause 5. Singing or hissing of brushes. This is usually 
occasioned by rough or sticky commutator (see Trouble I, Causes 
3 and 10), or by brushes not being smooth, or by the layers of a 
copper brush not being held together in place. With carbon 
brushes, hissing will be caused by the use of carbon that is gritty 
or too hard. Vertical carbon brushes, or brushes inclined against 
the direction of rotation, are liable to squeak or sing. Occasion- 


352 


MANAGEMENT OE DYNAMO-ELECTRIC MACHINERY 129 

ally, a new machine will make a noise that is reduced after the 
machine has been run for some time. 

Symptom . Sounds of high pitch are easily located by placing 
the ear near the commutator while it is running, and by lifting 
off the brushes one at a time—provided there are two or more 
brushes in each set, so that the circuit is not opened by lifting a 
single brush. If there is no current there is, of course, no objection 
to raising the brushes. 

Remedy. Apply a very little oil to the commutator with a rag 
on the end of a stick. Adjust the brushes or smooth the commu¬ 
tator by turning, or by using fine sandpaper, being careful to clean 
thoroughly afterwards. Carbon brushes are liable to squeak in 
starting up or at low speed. This squeaking decreases at full 
speed, and can generally be stopped altogether by moistening the 
brushes with oil, care being taken not to have any excess of oil. 
Running the machine without load for some time usually reduces 
this trouble. 

Cause 6. Flapping or pounding of belt joint or lacing 
against pulley. (Fig. 95.) 

Symptom. Sound repeated 
twice for each complete revolution 
of the belt, which is much less fre¬ 
quent than any other generator or 
motor sound, and can easily be detected or counted. 

Remedy. Endless belt or smoother joint. (See “Belting”, p. 8.) 

Cause 7. Slipping of belt on pulley due to overload. 

Symptom. Intermittent squeaking noise. 

Remedy. Tighten the belt or reduce the load. A wider belt 
or larger pulley may be required. Powdered rosin may be put 
on the belt to increase its adhesion; but such a procedure is a 
makeshift, is injurious to the belt, and should be adopted only 

when necessary. (See “Belting”, p. 7.) 

Cause 8. Humming of armature-core teeth as they pass the 

pole pieces. 

Symptom. Pure humming sound less metallic than Cause o. 

Remedy. Slope or chamfer the ends of the pole pieces so that 
each armature tooth does not pass the edge of the pole piece all 
at once. Decrease the magnetization of the fields. Increase the air 



Fig. 95. Typical Bad Belt Joints 


353 









130 MANAGEMENT OF DYNAMO-ELECTRTC MACHINERY 


gap or reduce the distance between the teeth. But these are nearly 
all matters of first construction and are made right by good 
manufacturers. 

Cause 9. Humming due to alternating or pulsating current. 

Symptom. This gives a sound similar to that in the preceding 
case. The two can be distinguished, if necessary, by determining 
whether the note given out corresponds to the number of alterna¬ 
tions or to the number of armature teeth passing per second. Usu¬ 
ally the latter is considerably greater than the former. 

Remedy. This trouble is confined to alternating apparatus, 
and its effects can be reduced by proper design and by mounting 
the machine so as to deaden the sound as far as possible; 

Note. —It often happens that a generator or motor seems to make a noise, 
which in reality is caused by the engine or other machine with which it is con¬ 
nected. Careful listening with the ear close to the different parts will show 
exactly where the noise originates. A very sensitive method of locating a 
noise or vibration is to place one end of a short stick between the teeth, and 
press the other end squarely against the various parts, to ascertain which par¬ 
ticular one gives the greatest vibration. 


VII. SPEED NOT RIGHT 


This is generally a serious matter in either a generator or a 
motor, and it is always desirable and often imperative to shut 
down immediately, and make a careful investigation. 


Speed Too Low 


Cause 1. Overload. (See I, Cause 1.) 

Symptom. Armature runs more slowly than usual. Bad 
sparking at commutator. Ammeter indicates excessive current. 
Armature heats. Belt very tight on tension side. 

Remedy. Reduce the load on machine, increase the diameter 
of driving pulley, or decrease the diameter of driven pulley. If 
necessary to relieve strain of overload, temporarily decrease the 
voltage on either a generator or a motor. 

Cause 2. Short circuit or ground in armature. 

Symptom and Remedy. Symptom and remedy the same as in 
case of III, Cause 2 and Cause 6. 




354 



MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 131 


Cause 3. Armature strikes pole pieces. 

Symptom and Remedy. Symptom and remedy the same as in 
the case of VI, Cause 2. 

Cause 4. Shaft does not revolve freely in the bearings. 

Symptom and Remedy. Symptom and Remedy the same as 
for Y, all cases. 

Cause 5. Poor contact in energy circuit. (This applies to 
single-phase repulsion motors only.) 

Symptom. As explained previously, the repulsion motor has 
one set of brushes short-circuited. These are the energy brushes 
and if there is a poor contact in this circuit, it will cause a reduc¬ 
tion in the output and in the speed of the motor. If this circuit 
is opened entirely, the motor will stop. 

Remedy. Test out this circuit by any resistance method, find 
the faulty connection, and repair it. 

Speed Too High or Too Low 

Cause 6. Field magnetism weak. This has the effect, on a 
constant-voltage circuit, of making a motor run too fast if lightly 
loaded, or too slow if heavily loaded. It makes a generator fail 
to 1 ‘ build up ” or excite its field, or give the proper voltage in any 
case. 

Symptom and Remedy. Symptom and remedy the same as in 
the case of “Sparking”, Cause 8. (See VII, Cause 7; also IX.) 

Cause 7. Too high or too low voltage on the circuit. 

Symptom. This would cause a motor to run too fast or too 
slow, respectively. It can be shown by measuring the voltage of 
the circuit. 

Remedy. The central station or generating plant should be 
notified that voltage is not right. 

Speed Too High 

Cause 8. Motor too lightly loaded. 

Symptom. A series-wound motor on a constant-potential cir¬ 
cuit runs too fast, and may speed up to the bursting point if the 
load is very much reduced or removed entirely (by the breaking 
of the belt, for example). 


355 


132 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 


Remedy. Care should be exercised in using a series motor 
on a constant-potential circuit, except where the load is a fan, 
pump, or other machine that is positively connected or geared to 
the motor so that there is no danger of its being taken off. A 
shunt- or compound-wound motor should be used, if the load is 
likely to be thrown off. 

Cause 9. Poor contact or open circuit in compensating cir¬ 
cuit. (This applies to single-phase repulsion motors only.) 

Symptom. No-load speed may be one and one-half times rated 
speed. 

Remedy. Look for poor contact or open circuit and test by 
resistance method. Repair contact or break. 


VIII. MOTOR STOPS OR FAILS TO START 

This is an extreme case of the previous class (“Speed Not 
Right”), but is separated because it is more definite and permits 
of quicker diagnosis and treatment. This heading does not, of 
course, apply to generators, since any trouble in setting these,in 
motion is usually outside of the machine itself. 

Cause 1. Great overload. A slight overload causes motor 
to run slowly, but an extreme overload will, of course, stop it en¬ 
tirely or “stall” it. (See I, Cause 1.) 

Symptom. Of course the chief symptom is the stopping of 
the motor. On a constant-potential circuit the current is excessive, 
and safety fuse blows or circuit breaker opens. In their absence 
or failure, armature is burnt out. 

Remedy. Turn off current instantly, reduce or take off the 
load, replace the fuse or circuit breaker, if necessary, and turn on 
current again just long enough to see if trouble still exists; if so, 
take off more load. 

Cause la. Load too great (a. c. motors). An induction 

motor if overloaded will'slow down somewhat, and finally stop 
altogether. It may also fail to start for the same reason. A 
synchronous motor will maintain its speed with any load it can 
carry. It will not start under too much load or will pull out of 
step and stop if overloaded while running. 

Symptom. The symptoms may be the same as in Cause 1. 


356 


MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 133 

Also there will be a pronounced humming indicating excessive 
current in the windings. 

Remedy. Apply remedies as given in Cause 1. 

Cause 2. Very excessive friction due to shaft, bearings, or 
other parts being jammed, or armature touching pole pieces. 

Symptom. Similar to previous case, but distinguished from 
it by the fact that the armature is hard to turn even when load is 
taken off. Examination shows that the shaft is too large or is 
bent or rough, that> the bearing is too tight, that the armature 
touches pole pieces, or that there is some other impediment to free 
rotation. (See V and YI.) 

Remedy. Turn current off instantly, ascertain and remove 
the cause of friction, turn on the current again just long enough 
to see if trouble still exists; if so, investigate.further. 

Cause 3. Circuit open. This may be due to (a) safety- 
fuse blown or circuit breaker open; (b) wire in motor broken or 
slipped out of connections; (c) brushes not in contact with com¬ 
mutator; (d) switch open; (e) circuit supplying motor open; (f) 
failure at generating plant. 

Symptom. Distinguished from Causes 1 and 2 by the fact 
that if the load is taken off, the motor still refuses to start, and yet 
armature turns freely. 

On a constant-potential d. c. circuit, the field circuit alone of a 
shunt motor may be open, in which case the pole pieces are not 
strongly magnetic when tested with a piece of iron, and there is 
a dangerously heavy current in the armature; if the armature 
circuit is at fault, there is no spark when the brushes are lifted; 
and if both are without current, there is no spark when switch is 
opened. One should be very careful if there is no field magnetism 
or even if it is very weak, as a motor is liable to be burnt out if 
the current is then thrown upon the armature. 

Remedy. Turn off current instantly. Examine safety fuse, 
circuit breaker, wires, brushes, switch, and circuit generally, for 
break or fault. If none can be found, turn on switch again for a 
moment, as the trouble may have been due to a temporary stop¬ 
page of the current at the station or on the line. If motor still 
seems dead, test separately armature, field coils, and other parts 
of circuit for continuity with a magneto, or a cell of battery and 


357 


134 MANAGEMENT OE DYNAMO-ELECTRIC MACHINERY 

an electric bell, to see if there is any break in the circuit. (See 
‘ 1 Instructions for Testing”, pages 88 to 93. 

One of the simplest ways to find whether the circuit has cur¬ 
rent in it and to locate any break, is to test through an incan¬ 
descent lamp. Two and five lamps in series should be used on 220- 
and 500-volt circuits, respectively. 

Cause 3a. Circuit open. (a. c. motors.) 

Symptom . In an a. c. motor there may be a pronounced hum¬ 
ming, showing that there is current in the motor, and yet it will 
not start. Even with no load the motor will not start, although 
the rotor may be turned by hand. 

Remedy. Turn off current. Check connections external to 
motor to locate any open circuit. If one phase only is open, allow¬ 
ing only single-phase current to reach the motor, it will not start 
and the fault can be repaired and the motor started. If no open 
circuit can be found, try again to start the motor, since the circuit 
from the power house may have been temporarily interrupted. If 
the motor still fails to start, the trouble must be from an open 
circuit within the motor and the usual tests for this condition will 
have to be made. It may be necessary in this case to remove some 
coils and replace them with new ones. If it is an induction motor 
with an external resistance in the rotor circuit, a test should be 
made for grounds or short circuits in the resistance. Sucn grounds 
or shorts can usually be easily found and removed. 

In addition to the above, there may be an open circuit in some ; 
auxiliary apparatus, such as a transformer or starting compen¬ 
sator. Tests for open circuits should be applied to these auxiliaries 
as well as to the motor and the breaks or loose connections repaired. 

Cause 4. Wrong connection or complete short circuit of 
field, armature, switch, etc. 

General Symptom. Distinguished from Causes 1 and 2 in the 
same way as Cause 3, and differs from Cause 3 in the evidence of 
strong current in motor. 

Symptom on a constant-potential circuit. If current is very 
great it indicates a short circuit. If the field is at fault it will not 
be strongly magnetic. 

The possible complications of wrong connections are so great 
that no exact rules can be given. Carefully examine and make 


358 




MANAGEMENT OE DYNAMO-ELECTRIC MACHINERY 135 

sure of the correctness of all connections (see “Diagram of Con¬ 
nections ” accompanying the machine). This trouble is usually 
inexcusable, since only a competent person should ever set up a 
machine or change its connections. 

Symptoms in the three-ivire (220-volt direct-current) system * 
Several peculiar conditions may exist, as follows: 

(a) The generator or generators on one side of the system may 
become reversed, so that both of the outside wires are positive or 
negative. In that case a motor fed in the usual way from the two 
outside wires will get no current, but lamps connected between the 
neutral wire and either of the outside wires will burn as usual. 

(b) If one of the outside wires is open by the blowing of a 
fuse, an accidental break, or other cause, then a motor (220-volt) 
beyond the break can get some current at 110 volts through any 
lamps that may be on the same side of the break as itself, and on 
the same side of the system as the conductor that is open. These 
lamps will light up when the motor is connected, but the motor 
will have little or no power unless the number of lamps is large. 

(c) If the neutral or middle wire is open, a motor connected 
with the outside wires will run as usual; but lamps on one side of 
the system will burn more brightly than those on the other side, 
unless the two sides are perfectly balanced. 

(d) If one of the outside wires becomes accidentally grounded, 
a 110-volt generator, motor, or other apparatus, also grounded and 
connected to the other outside wire, will receive 220 volts, which 
will probably burn it out. 

Polyphase Induction Motor Operates Sing1e=Phase 

Cause. Open circuit in one lead. 

Symptom. Motor will net carry full rated load and heats 
too much. Motors are often started with the fuses cut out. In 
that case the motor would start satisfactorily and a blown fuse in 
one leg would not be discovered. After once up to speed, the 
motor could be thrown over to running position and would run 
single-phase, but would carry only a part of its load (about 70 per 

cent for a three-phase motor). 

Remedy. Locate the break in the circuit and replace the fuse 

or repair the break. 


S59 





136 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

Synchronous Motor Fails to Reach Synchronous Speed 

Cause 1. Short-circuited field. 

Symptom. Motor starts, but comes up to a speed far below 
synchronism and sticks at that speed. This speed is not high 
enough to allow the starting switch to be thrown over into full 
voltage position. 

Remedy. Open the circuit. Examine the revolving field for 
external short circuits, or shorts in the connections between spools 
and collector rings. If a resistance is used across the fields in 
starting, it may be short-circuited, thus shorting the fields. Test 
the field circuit for grounds which might cause short circuits. 
Remove any shorts discovered. The motor will then come within 
about 5 per cent of full speed on the starting tap of the trans¬ 
former or compensator and can be thrown on full voltage and 
given current in the fields. 

Cause 2. Too much load. 

Symptom. The motor may fail entirely to start, or may 
come up to sub-synchronous speed as in the previous case. 

Remedy. Remove some of the load, or arrange a clutch so 
that the load can be applied after the motor is on the line and 
running at full speed. If neither of these methods can be used, 
an auxiliary induction motor may be belted to the motor to help 
it up to speed. 

Synchronous Motor Flashes Across Collector Rings or End Field 
Coils at Starting 

Cause. High voltage induced in fields. 

Symptom. When starting switch is first thrown in, a bad 
flash appears at the collector rings or field coils. 

Remedy. Insert a properly designed resistance so that it is 
across the fields during the starting operation. This resistance 
will prevent the rise in voltage, which, in some machines, may 
reach a value as high as 2500 or 3000 volts. 

IX. DYNAMO FAILS TO GENERATE 

This trouble is almost always caused by the inability of a 
generator to “build up” or excite its field-magnetism sufficiently. 
The proper starting of a self-exciting machine requires a certain 


360 



MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 137 


amount of residual magnetism, which must be increased to full 
strength by the current generated in the machine itself. This 
trouble is not likely to occur on a separately-excited machine; 
and if it does, it is usually due to the exciter failing to generate, 
and therefore amounts to the same thing. 

Cause 1. Residual magnetism too weak or destroyed. 

This may be due to (a) vibration or jar; (b) proximity of 
another generator ; (c) earth’s magnetism; (d) accidental reversed 
current through fields, not enough to completely reverse mag¬ 
netism. The complete reversal of the residual magnetism in any 
machine will not prevent its generating, but will only make it 
build up of opposite polarity. Sometimes reversal of residual 
magnetism may be very objectionable, as in case of charging 
storage batteries, but, although the popular supposition is to the 
contrary, it will not cause the machine to fail to generate. 

Symptom. Little or no magnetic attraction when the pole 
pieces are tested with a piece of iron. 

Remedy. Send a magnetizing current from another machine 
or battery through the field coils, then start and try the machine; 
if this fails, apply the current in the opposite direction, since the 
magnets may have enough polarity to prevent the battery building 
them up in the direction first tried. 

Shift the brushes backward in a generator or forward in a 
motor to make armature magnetism assist field. 

Cause 2. Reversed connections or reverse direction of rota¬ 
tion. 

Symptom. When running, pole pieces show no attraction for 
a piece of iron. The application of external current cannot be 
made to start the machine, as in the case of Cause 1, because, 
whichever way the field may be magnetized, the resulting current 
generated by armature opposes and destroys the magnetism. 

Remedy, (a) Reverse either armature connections or field 
connections, but not both, (b) Move brushes through 180 degrees 
for two-pole, 90 degrees for four-pole machines, etc. (c) Reverse 
direction of rotation. After each of the above are tried, the field 
may have to be built up with a battery or other current, since the 
causes in this case tend to destroy whatever residual magnetism 
may have been present. 


361 


138 MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 

Cause 3. Short circuit in the machine or external circuit. 

This applies to a shunt-wound machine, and has the effect of 
preventing the voltage and the field magnetism from building up. 

Symptom. Magnetism weak, but still quite perceptible. 

Remedy. If the short circuit is in the external circuit, open¬ 
ing the latter will allow the dynamo to build up and generate full 
voltage. If the short circuit is within the machine, it should be 
found by careful inspection or testing. In either of these cases, 
do not connect the external circuit until short circuit is found 
and eliminated. A slight short circuit, such as that caused by 
copper dust on the brush holder or commutator, may prevent the 
magnetism of a shunt machine from building up. (See “Spark¬ 
ing”, I, Causes 5 and 8.) Too much load might prevent a shunt 
dynamo from building up its field magnetism, in which case the 
load, or some of it, should be disconnected in starting. 

Cause 4. Field coils opposed to each other. 

Symptom. Upon passing a current from another source of 
supply, the following symptom will exist: If the pole pieces of a 
bipolar machine are approached with a compass or other freely 
suspended magnet, they both attract the same end of the magnet, 
showing them to be of the same polarity, whereas they should 
always be of opposite polarity. 

For similar reasons the pole pieces are magnetic when tested 
separately with a piece of iron, but show less attraction when the 
same piece of iron is applied to both at once, in which latter case 
the attraction should be stronger. In multipolar machines these 
tests should be applied to consecutive pole pieces. 

Remedy. Reverse the connections of the incorrectly connected 
coils in order to make the polarity of the pole pieces opposite. 
The pole pieces should be alternately north and south. 

Cause 5. Open circuit. This may be due to (a) broken 
wire or faulty connection in machine; (b) brushes not in c'ontact 
with commutator; (c) safety fuse melted or absent; (d) switch 
open; (e) external circuit open. 

Symptom. If the trouble is merely due to the switch or 
external circuit being open, the magnetism of a shunt generator 
may be at full strength, and the machine itself may be working 


362 


MANAGEMENT OF DYNAMO-ELECTRIC MACHINERY 139 

perfectly; but if the trouble is in the machine, the field mag¬ 
netism will probably be very weak. 

Remedy. Make a very careful examination for open circuit; 
if not found, test separately the field coils, armature, etc., for 
continuity, with magneto or cell of battery and electric bell. (See 
Instructions for Testing”, p. 92, also VIII, Cause 3.) 

A break, poor contact, or excessive resistance in the field 
circuit or field rheostat of a shunt dynamo will also make the 
magnetism weak and prevent its building up. This may be 
detected and overcome by cutting out the rheostat for a moment 
by connecting the two terminals of the field coils to the two 
brushes respectively, care being taken not to make a short circuit. 

A break or abnormally high resistance anywhere in the 
.external circuit of a series-wound dynamo will prevent it from 
generating, since the field coil is in the main circuit. This may. 
be detected and overcome by short-circuiting the machine for a 
moment in order to start up the magnetism. 

Either of these two remedies by short-circuiting should be 
applied very carefully, and not until the pole-pieces have been 
tested with a piece of iron to make sure that the magnetism is weak. 

Cause 6. Brushes not in proper position. 

Symptom. The strength of the field increases, and the volt¬ 
age of the generator builds up. 

Remedy. It sometimes happens that brushes are not set at 
the proper point on commutator and, if the residual magnetism is 
already weak, the machine may fail to build up. Almost all modern 
generators made in this country have the brushes set about oppo¬ 
site the center of the pole piece. Generators require the brushes 
to be shifted in the direction of rotation of the armature; motors 
require a backward shift to the brushes. Occasionally a generator 
may be found with armature wound in such a way that the proper 
position of the brushes is midway between the adjacent pole tips. 

X. VOLTAGE OF GENERATOR NOT RIGHT 

Cause 1. Speed too low. (See VII.) 

Remedy. Increase speed of the prime mover if possible; 
when this cannot be done, decrease the diameter of the driven 


363 


140 MANAGEMENT OP DYNAMO-ELECTRIC MACHINERY 

pulley or increase the diameter of the driving pulley, preferably | 
the latter. 

Cause 2. Field magnetism weak. 

Symptom and Remedy. See I, Cause 8. 

Cause 3. Brushes not in proper position. 

Symptom and Remedy. See I, Cause 2. 

Cause 4. Machine overloaded. 

Symptom and Remedy. See I, Cause 1, and VII, Cause 1; 
also increase field excitation, if possible. 

Cause 5. Short-circuited armature coil or coils. 

Symptom and Remedy. See I, Cause 5. 

Cause 6. Reversed armature coil or coils. 

Symptom and Remedy. See I, Cause 5. 

Voltage Too High 
Cause 7. Speed too high. 

Remedy. Apply the reverse of treatment given in Cause 1. 
Cause 8. Field magnetism too powerful. 

Remedy. Increase resistance of shunt-field circuit, by means 
of a shunt-field rheostat. 

Cause 9. Machine compounds too much. 

Remedy. Decrease resistance of series-field shunt. (See 
“Compound-Wound Dynamos”, page 17, Part I.) 

In commutating-pole generators it sometimes happens that 
the commutating poles themselves exert a compounding effect; 
especially is this true if the brushes are shifted slightly back of the 
proper neutral point. 


364 














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POWER STATIONS 

INTRODUCTION 

With the rapid increase of. the use of electricity for power, 
lighting, traction, and electro-chemical processes, the power houses 
equipped for the generation of the electrical supply have increased 
in size from plants containing a few low-capacity dynamos, belted 
t° their P rim e movers and lighting a limited district, to the modern 
central station, furnishing power to immense systems and over 
extended areas. Examples of the latter type of station are found 
at Niagara Falls, and such stations as the Metropolitan and Man¬ 
hattan stations in New York City, and the plants of the Boston 
Edison Illuminating Company, etc. 

The subject of the design, operation, and maintenance of cen¬ 
tral^ stations forms an extended and attractive branch of electrical 
engineering. The design of a successful station requires scientific 
training, extensive experience, and technical ability. Knowledge 
of electrical subjects alone will not suffice, as civil and mechanical en¬ 
gineering ability is called into play as well, while ultimate success 
depends largely on financial conditions. Thus, with unlimited 
capital, a station of high economy of operation may be designed 
and constructed, but the business may be such that the fixed charges 
for money invested will more than equal the difference between the 
receipts of the company and the cost of the generation of power 
alone. In such cases it is better to build a cheaper station and one 
not possessing such extremely high economy, but on which the 
fixed charges are so greatly reduced that it may be operated at a profit 
to the owners. 

The designing engineer should be thoroughly familiar with 
the nature and extent of the demand for power and with the prob¬ 
able increase in this demand. Few systems can be completed for 
their ultimate capacity at first and, at the same time, be operated 
economically. Only such generating units, with suitable reserve 
capacity, as are necessary to supply the demand should be installed 


367 



2 


POWER STATIONS 


at first, but all apparatus should be arranged in such a manner that 

future extensions can readily be made. 

Power stations, as here treated, will be considered under the 

following general topics: 

Location of Station 
Steam Plant 
Hydraulic Plant 

Gas Plant jj 

Electric Plant 
Buildings 
Station Records 

LOCATION OF STATION 

The choice of a site for the generating station is very closely 
connected with the selection of the system to be used, which sys¬ 
tem, in turn, depends largely on the nature of the demand, so that 
it is a little difficult to treat these topics separately. Several possi¬ 
ble sites are often available, and we may either consider the require¬ 
ments of an ideal location, selecting the available one which is 
nearest to this in its characteristics, or we may select the best system 
for a given area and assume that the station may be located where ■ 
it would be best adapted to this system. Wherever the site may 
be, it is possible to select an efficient system, though not always an 
ideal one. 

The points that should be considered in the location of a station, 
no matter what the system used, are accessibility, water supply, 
stability of foundations, surroundings, facility for extension, and 
cost of real estate. 

I Accessibility. The station should be readily accessible on ac¬ 
count of the delivery of fuel, of stores, and of machinery. It should 
be so located that ashes and cinders may easily be removed. If 
possible, the station should be located so as to be reached by both 
rail and water, though the former is generally more desirable. If 
the coal can be delivered to the bunkers directly from the cars, the 
very important item of the cost of handling fuel may be greatly 
reduced. Again, the station should be in such a location that it may 
readily be reached by the workmen. 

Water Supply. Cheap and abundant water supply for both 
boilers and condensers is of utmost importance in locating a steam 


368 


POWER STATIONS 


3 


station. The quality of the water supply for the boiler is of more 
importance than the quantity. It should be as free as possible from 
impurities which are liable to corrode the boilers, and for this 
reason water from the town mains is often used, even when other 
water is available, as it is possible to economize in the use of 
water by the selection of proper condensers. The supply for 
condensing purposes should be abundant, otherwise it is necessary 
to install extensive cooling apparatus, which is costly and occupies 
much space. 

Stabilityof Foundations. The machinery, as well as the buildings, 
must have stable foundations, and it is well to investigate the avail¬ 
ability of such foundations when selecting the site. 

Surroundings. In the operation of a power plant using coal or 
other fuels, certain nuisances arise, such as smoke, noise, vibration, 
etc. For this reason it is preferable to locate where there is little 
liability to complaint on account of these causes, as some of these 
nuisances are costly and difficult, or even impossible, to prevent. 

Facility for Extension. A station should be located where there 
are ample facilities for extension and, while it may not always be 
advisable to purchase land sufficient for these extensions at first, 
if there is the slightest doubt in regard to being able to purchase it 
later, it should be bought at once, as the station should be as free 
as possible from risk of interruption of its plans. Often real estate 
is too high for purchasing a site in the best location, and then the 
next best point must be selected. A consideration of all the factors 
involved is necessary in determining whether or not this cost is too 
high. In densely populated districts it is necessary to economize 
greatly with the space available, but it is generally desirable that 
all the machinery be placed on the ground floor and that adequate 
provision be made for the storage of fuel, etc. 

Cost of Real Estate. The location of substations is usually fixed 
by other conditions than those which determine the site of the main 
power house. Since, in the simple rotary-converter substation, 
neither fuel nor water is necessary, and there is little noise or vibra¬ 
tion, it may be located wherever the cost of real estate will permit, 
provided suitable foundations may be constructed. The distance 
between substations depends entirely on the selection of the system 
and the nature of the service. 


369 


4 


POWER STATIONS 


GENERAL FEATURES 

Miscellaneous Considerations. Where low voltages are used, 
it is essential that the station be located as near the center of the 
system as possible. .This center is located as follows: 

' Having determined the probable loads and their points of 
application for the proposed system, these loads are indicated on a 
drawing with the location of the same shown to scale. The center 
of gravity of this system, considering each load as a weight, is then 
found and its location is the ideal location, as regards amount of 
copper necessary for the distributing system. 

Consider Fig. 1, which shows the location of five different 


Fig. 1. Graphical Method of Locating Center of the System 

loads, indicated in this case by the number of amperes. Combining 
loads A and B, we have 

Ax — By x + y = a 

Solving these equations, we find that A and B may be considered as 
a load of A + B amperes at F. Similarly, C and D, E and F, and 
G and II may be combined giving us I, the center of the system. 
The amount of copper necessary for a given regulation runs up 
very rapidly as the distance of the station from this point in¬ 
creases. Where there are obstructions which will not permit the 
feeders to be run in an approximately straight line, the distance 
A B, etc., should be measured along the line the conductors must 
take. 



370 


POWER STATIONS 


Selection of System. General rules only can be stated for the 
selection of a system to be used in any given territory for a certain 
class of service. 

For an area not over two miles square and a site reasonably 
near the center, direct-current, low-pressure, three-wire systems 
may be used for lighting and ordinary power purposes. Either 220 
volts or 440 volts may be used as a maximum voltage, and motors 
should, preferably, be connected across the outside wires of the cir¬ 
cuits. Five-wire systems with 440 volts maximum potential have 
been used, but they require very careful balancing of the load if the 
i service is to be satisfactory. 220-volt lamps are giving good satis- 
i faction; moderate-size, direct-current motors may readily be built 
for this pressure and constant-potential arc lamps may be operated 
i on this voltage, though not so economically as on 110 volts, if single 
lamps are used. The new types of incandescent lamps in low candle- 
power units are not suitable for 220 volts. For direct-current rail¬ 
way work, the limit of the distance to which power may be economic¬ 
ally delivered with an initial pressure of 600 volts is from five to 
seven miles, depending on the traffic. 

If the area to be served is materially larger than the above, 
or distances for direct-current railways greater, either of the two 
following schemes may be adopted: (1) Several stations may be 
located in the territory and operated separately or in multiple on 
the various loads; or (2) one large power house may be erected and 
the energy transmitted from this station at a high voltage to various 
transformers or transformer substations which, in turn, transform 
the voltage to one suitable for the receivers. Local conditions usually 
determine which of these two shall be used. The alternating-current 
system with a moderate potential—about 2,300 volts for the primary 
lines—is now often installed for very small lighting systems. 

The use of several low-tension stations operating in multiple 
is recommended only under certain conditions, namely, that the 
demand is very heavy and fairly uniformly distributed throughout 
the area, and suitable sites for the power house can readily be ob¬ 
tained. Such conditions rarely exist and it is a question whether 
or not the single station would not be just as suitable for such cases 
as where the load is not so congested. 

One reason why a large central station is preferred to several 


371 



6 


POWER STATIONS 


smaller stations is that large stations can be operated more eco¬ 
nomically, owing to the fact that large units may be used and they 
can be run more nearly at full load. There is a gain in the cost 
of attendance, and labor-saving devices can be more profitably in¬ 
stalled. The location of the power plant is not determined to such 
a large extent by the position of the load, but other conditions, 
such as water supply, cheap real estate, etc., will be the governing 
factors. In several cities, notably New York, Chicago, and Boston, 
large central stations are being installed to take the place of several 
separate stations, the old stations being changed from generating 
power houses to rotarv-converter substations. Both direct-current 
low-tension machines—for supplying the neighboring districts—and 
high-tension alternating-current machines—for supplying the out, 
lying or residence districts—are often installed in the one station. 

As examples of the central station located at some distance 
from the center of the load, we have nearly all of the large hydraulic 
power developments. Here it is the cheapness of the water power 
which determines the power-house location. The greatest distance 
over which power is transmitted electrically at present is in the 
neighborhood of 200 miles. 

If a high-tension alternating-current system is to be installed, 
there remains the choice of a polyphase or single-phase machine 
as well as the selection of voltage for transmission purposes. As 
pointed out in “Power Transmission,” polyphase generators are 
cheaper than single-phase generators and, if necessary, they can be 
loaded to about 80 per cent of their normal capacity, single-phase, 
while motors can more readily be operated from polyphase circuits. 
If synchronous motors or rotary converters are to be installed, a 
polyphase system is necessary. The voltage will be determined by 
the distance of transmission, care being taken to select a value con¬ 
sidered as standard, if possible. Generators are wound giving a 
voltage at; the terminals as high as 15,000 volts, but in many dis¬ 
tricts it is desirable to use step-up transformers for voltages above 
6,600 on account of liability to troubles from lighting. 

With the development of the single-phase railway motor, cen¬ 
tral stations generating single-phase current only, are occasionally 
built in larger sizes than previously, as their use heretofore has been 
limited to lighting stations. 


372 


POWER STATIONS 


7 


Factors in Design. A few general notes in regard to the design 
of plants will be given here, the several points being taken up more 
in detail later. 

Direct driving of apparatus is always superior to methods of 
gearing or belting as it is efficient, safe, and reliable, but it is not as 
flexible as shafting and belts, and ‘on this account its adoption is 
not universal. 

Speeds to be used will depend on the type and size of the gen¬ 
erating unit. Small machines are always cheaper when run at high 
speeds, but the saving is less on large generators. For large engines 
slow speed is always preferable. 

It is desirable that there be a demand for both power and 
lighting, and a station should be constructed which will serve both 
purposes. The use of power will create a day load for a lighting 
station, which does much to increase its ultimate efficiency and, as 
a rule, its earning capacity. 

In addition to generator capacity necessary to supply the load, 
a certain amount of reserve, either in the way of additional units 
or overload capacity, must be installed. The probable load for, say 
three years, can be closely estimated, and this, together with the 
proper reserve, will determine the size of the station. The plant 
as a whole, including all future extensions, should be planned at 
the start as extensions will then be greatly facilitated. Usually it 
will not be desirable to begin extensions for at least three years 
after the first part of the plant has been erected. 

Enough units must be installed so that one or more may be 
laid off for repairs, and there are several arguments in favor of 
making this reserve in the way of overload capacity, for the gen¬ 
erators at least. Some of these arguments are: 

Reserve is often required at short notice, notably in railway plants. 

With overload capacity the rapid increase of load, such as occurs in 
lighting stations when darkness comes on suddenly, may more readily be taken 
care of. 

There is always a factor of safety in machines not running to their 
fullest capacity. 

Reserve capacity is cheaper in this form than if installed as separate 
machines. 

As a disadvantage, we have a lower efficiency, due to machines not usually 
running at full load, but in the case of generators this is very slight. 


373 


8 


POWER STATIONS 


TABLE I 


Permissible Overload 33 Per Cent 



Machines added 
one at a time 

Machines added 
two at a time 

Machines added 
three at a time 

No. 

Size. 

No. 

Size. 

No. 

Size. 

Initial installment 

4 

500 

4 

500 

4 

500 

First extension 

1 

666 

2 

1000 

3 

2000 

Second extension 

1 

888 

2 

2000 

5 

5000 

Third extension 

1 

1183 

2 

4000 

4 

5000 

Fourth extension 

1 

1577 

4 

4000 



Fifth extension 

1 

2103 

8 

4000 



Sixth extension 

1 

2804 






With an overload capacity of 33J per cent, four machines should 
be the initial installment, since one can.be laid off for repairs, if 
necessary, the total load being readily carried by three machines. 
In planning extensions, the fact that at least one machine may 
require to be laid off at any time should not be lost sight of, while 
the units should be made as large as is conducive to the best opera¬ 
tion. 

Table I is worked out showing the initial installment for a 
2,000-kw. plant with future extensions. It is seen from this table 
that adding two machines at a time gives more uniformity in the 
size of units—a very desirable feature. 

Tte boilers should be of large units for stations of large capacity, 
while for small stations they must be selected so that at least one 
may be laid off for repairs. 


STEAM PLANT 
BOILERS 

The majority of power stations have as their prime movers 
either steam or water power, though there are many using gas. 
If steam is the power selected, the subject of boilers is one of vital 
importance to the successful operation of central stations. The 
object of the boiler with its furnace is to abstract as much heat as 
possible from the fuel and impart it to the water. The various kinds 
of boilers used for accomplishing this more or less successfully are 
described in books on boilers, and we will consider here the merits 
of a few of the types only as regards central-station operation. 


374 


















POWER STATIONS 


9 


The considerations are: (1) Steam must be available through¬ 
out the twenty-four hours, the amount required at different parts 
of the day varying considerably. Thus, in a lighting station, the 
demand from midnight to 6 a. m. is very light, but toward evening, 
when the load on the station increases very rapidly, there is an abrupt 
increase in the rate at which steam must be given off. The maxi¬ 
mum demand can readily be anticipated under normal weather 
conditions, but occasionally this maximum will be equaled or even 
exceeded at unexpected moments. For this reason a certain num¬ 
ber of boilers must be kept under steam constantly, more or less of 
them running with banked fires during light loads. If the boilers 
have a small amount of radiating surface, the loss during idle hours 
will be decreased. 

(2) The boilers must be economical over a large range of 
rates of firing and must be capable of being forced without detriment. 
Boilers should be provided which work economically for the hours 
just preceding and following the maximum load while they may 
be forced, though running at lower efficiency, during the peak. 

(3) Coming to the commercial side of the question, we have 
first cost, cost of maintenance, and space occupied. The first 
cost, as does the cost of maintenance, varies with the type and 
the pressure of the boiler. The space occupied enters as a factor 
only when the situation of the station is such that space is limited, 
or when the amount of steam piping becomes excessive. In some 
city-plants, space may be the determining feature in the selection of 
boilers. 

Classification. Boilers for central stations may be classified as 
fire-tube and water-tube types. Of the former may be mentioned 
the Cornish, Lancashire, Galloway, multitubular, marine, and 
economic boilers. The Babcock and Wilcox, Stirling, and Heine 
boilers are examples of the water-tube type. 

Fire-Tube Boilers. The Cornish and Lancashire boilers have 
the fire tubes of such a diameter that the furnaces may be constructed 
inside of them. They differ only in the number of cylindrical tubes 
in which the furnaces are placed, as many as three tubes being placed 
in the largest sizes (seldom used) of the Lancashire boilers. They 
are made ro to 200-pound steam pressure and possess the following 
features: 


375 


10 


POWER STATIONS 


X. High efficiency at moderate rates of combustion 

2. Low rate of depreciation 

3. Large water space 

4. Easily cleaned 

5. Large floor space required 

6. Cannot be readily forced 

The Galloway boiler differs from the Lancashire boiler in that 
there are cross-tubes in the flues. 

In the multitubular boiler, the number of tubes is greatly increased 
and their size is diminished. Their heating surface is large and 
they steam rapidly. They require a separate furnace and are used 
extensively for. power-station work. 

Marine boilers require no setting. Among their advantages 
and disadvantages may be mentioned: 

1. Exceedingly small space necessary 

2. Radiating surface reduced 

3. Good economy 

4. Heavy and difficult to repair 

5. Unsuitable for bad water 

6. Poor circulation of water 

The economic boiler is a combination of the Lancashire and 
multitubular boilers, as is the marine boiler. It is set in brickwork 
and arranged so that the gases pass under the bottom and along the 
sides of the boiler as well as through the tubes. It way be com¬ 
pared with other boilers from the following points: 

1. Small floor space 

2. Less radiating surface than the Lancashire boiler 

3. Not easily cleaned 

4. Repairs rather expensive 

5. Requires considerable draft 

Water-Tube Boilers. The chief characteristics of the water-tube 
boilers, of which there are many types, are 

1. Moderate floor space 

2. Ability to steam rapidly 

3. Good water circulation 

4. Adapted to high pressure 

5. Easily transported and erected 

6. Easily repaired 

7. Not easily cleaned 

8. Rate of deterioration greater than for Lancashire boiler 

9. Small water space, hence variation in pressure with varying de¬ 

mands for steam 

10. Expensive setting 


376 


POWER STATIONS 


11 


Initial Cost. As regards first cost, boilers installed for 150- 
pound pressure and the same rate of evaporation, will run in the 
following order: Galloway and Marine, highest first cost, Economic, 
Lancashire, and Babcock and Wilcox. The increase of cost, with 
increase of steam pressure, is greatest for the Economic and least 
for the water-tube type. 

Deterioration. Deterioration is less with the Lancashire boiler 
than with the other types. 

Floor Space. The floor space occupied by these various types 
built for 150 pounds pressure and 7,500 pounds of water, evaporated 
per hour, is given in Table II. 


TABLE II 

Boiler Floor Space 


Kind of Boiler 

Floor Space in sq. ft. 

Lancashire 

408 

Galloway 

371 

Babcock and Wilcox 

200 

Marine wet-back 

120 

Economic 

210 


Efficiency.' The percentage of the heat of the fuel utilized by 
the boiler is of great importance, but it is difficult to get reliable 
data in regard to this. Table III* will give some idea of the effi¬ 
ciencies of the different types. The efficiency is more a question of 
proper proportioning of grate and heating surface and condition of 
boiler than of the type of boiler. Economizers were not used in any 
of these tests, but they should always be used with the Lancashire 
type of boiler. 

It is well to select a boiler from 20 to 50 pounds in excess of 
the pressure to be used, as its life may thus be considerably ex¬ 
tended, while, when the boiler is new, the safety valve need not 
be set so near the normal pressure, and there is less steam wasted 
by the blowing off of this valve. Again, a few extra pounds of 
steam may be carried just previous to the time the peak of the 
load is expected. For pressures exceeding 200 or, possibly, 150 
pounds, a water-tube boiler should be selected. 

In large stations, it is preferable to make the boiler units of 

*From Donkin’s “Heat Efficiency of Steam Boilers.” 


377 















POWER STATIONS 


12 


TABLE III 
Boiler Efficiencies 


Kind of Boiler 

No. of Ex¬ 
peri¬ 
ments 

Mean Ef¬ 
ficiency 

OF TWO 

best Ex¬ 
periments 

Lowest 

Effi¬ 

ciency 

Mean Ef¬ 
ficiency 

OF ALL 

Experi¬ 

ments 

Lancashire hand-fired 

107 

79.5 

42.1 

62.3 

Lancashire machine-fired 

40 

73.0 

51.9 

64.2 

Cornish hand-fired 

25 

81.7 

53.0 

68.0 

Babcock and Wilcox hand-fired 

49 

77.5 

50.0 

64.9 

Marine wet-back hand-fired 

6 

69.6 

62.0 

66.0 

Marine dry-back hand-fired 

24 

75.7 

64.7 

69.2 


large capacity, to do away as much as possible with the extra piping 
and fittings necessary for each unit. Water-tube boilers are best 


i 



VALVE. 

Fig. 2. Diagram of Ring System of Piping 




adapted for large sizes. These may be constructed for 150-pound 1 
pressure, large enough to evaporate 20,000 pounds of water pei i 
hour, at an economical rate. 


378 




























































POWER STATIONS 


13 


Boilers of the multitubular type or water-tube boilers are used 
in the majority of power stations in the United States. For stations 
of moderate size, with medium steam pressures and plenty of space, 
the return tubular boiler is often employed. For the larger stations 
and the higher steam pressures, the water-tube boilers are employed. 
Marine or other special types are used only occasionally where space 
is limited or where other local conditions govern. 

Steam Piping. The piping from the boilers to the engines 
should be given very careful consideration. Steam should be avail- 



Fig. 3. Diagram of Ring System with Cross-Connections 


able at all times and for all engines. Freedom from serious inter¬ 
ruptions due to leaks or breaks in the piping is brought about by 
very careful design and the use of good material in construction. 


379 

















































14 


POWER STATIONS 


Duplicate piping is used in many instances. Provision must always 
be made for variations in length of the pipe with variation of tem¬ 
perature. For plants using steam at 150-pound pressure, the varia¬ 
tion in the length of steam pipe may be as high as 2.5 inches for 100 
feet, and at least 2 inches for 100 feet should always be counted 
upon. 

Arrangement Fig. 2 shows a simple diagram of the ring system 
of piping. The steam passes from the boiler by two paths to the 
engine and any section of the piping may be cut out by the closing 
of two valves. Simple ring systems have the following characteristics: 

1. The range, as the main pipe is called, must be of uniform size and 
large enough to carry all of the steam when generated at its maximum rate. 

2. A damaged section may disable one boiler or one engine. 

3. Several large valves are required. 

4. Provision may readily be made to allow for expansion of pipes. 

Cross-connecting the ring system, as shown in Fig. 3, changes 
these characteristics as follows: 

1. Size of pipes and consequent radiating surface is reduced. 

2. More valves are needed but they are of smaller size. 

3. Less easy to arrange for expansion of the pipes. 

If the system is to be duplicated, that is, two complete sets of 
main pipes and feeders installed, Fig. 4, two schemes are in use: 

1. Each system is designed to operate the whole station at maximum 
load with normal velocity and loss of pressure in the pipes, and only one system 
is in use at a time. This has the disadvantage that the idle section is liable 
not to be in good operating condition when needed. Large pipes must be 
used for each set of mains. 

2. The two systems may be made large enough to supply steam at nor¬ 
mal loss of pressure when both are used at the same time, while either is made 
large enough to keep the station running should the other section need repairs. 
This has the advantages of less expense, and both sections of pipe are normally 
in use; but it has the disadvantages of more radiating surface to the pipes 
and consequent condensation for the same capacity for furnishing steam. 

Complete interchangeability of units cannot be arranged for 
if the separate engine units exceed 400 to 500 horse-power. Since 
engine units can be made larger than boiler units, it becomes neces¬ 
sary to treat several boiler units as a single unit, or battery, these 
batteries being connected as the single boilers already shown. For 
still larger plants the steam piping, if arranged to supply any engines 
from any batteries of boilers, would be of enormous size. If the 


380 


POWER STATIONS 


15 


boilers do not occupy a greater length of floor space than the engines, 
Fig. 5 shows a good arrangement of units. Any engine can be fed 
from either of two batteries of boilers and the liability of serious 
interruptions of service due to steam pipes or boiler trouble is very 
remote. 

In many plants but a single steam range is used, the station 
depending upon good material, careful construction, and thorough 



I 

"I n 

i ' 

_i 1_ 



i i 

n 



I i 

II 
i 1 

J L _ 

--— i 


1 i 

i i 




— rr~ 

11 

11 

. _J L 



'“1C 




l 7 

11 

11 

1 L 




'll" ' 

i i 







u 

11 

11 

J L 

— 

"ir 






y 

n 

u 


Fig, 4. Duplicate System of Piping 


inspection for reliability of service. In the largest steam-turbine 
stations, the so-called unit system is employed as is explained later 
under “Station Arrangement.” 

Material. Steel pipe, lap welded and fastened together by 
means of flanges, is to be recommended for all steam piping. The 
flanges may be screwed on the ends of sections and calked so as to 
render this connection steam tight, though in large sizes it is better 
to have the flanges welded to the pipes. This latter construction 


381 







































































16 


POWER STATIONS 


costs no more for large pipes and is much more reliable. All valves 
and fittings are made in two grades or weights, one for low pressures, 
and the other for high pressures. The high-pressure fittings should 
always be used for electrical stations. Gate valves should always 



/3 O/LUFtS 


Fig. 5. Arrangement of Boilers anfi Engines 
in Very Large Plants* 


be selected, and, in large sizes, they should be provided with a by-pass. 

Asbestos, either alone or with copper rings, vulcanized India 
rubber, asbestos and India rubber, etc., are used for packing between 
flanges to render them steam tight. Where there is much expansion, 
the material selected should be one that possesses considerable 


382 















































POWER STATIONS 


17 


elasticity. Joints for high-pressure systems require much more 
care than those for low-pressure systems, and the number of joints 
should be reduced to a minimum by using long sections of pipe. 

F ittings. A list of the various fittings required for steam piping, 
together with their descriptions, is given in books on boilers. One 
precaution to be taken is to see that such fittings do not become too 
numerous or complicated, and it is well not to depend too much on 
automatic fittings. Steam separators should be large enough to 
serve as a reservoir of steam for the engine and thus equalize, to a 
certain extent, the velocity of flow of steam in the pipes. 

Expansion. In providing for the expansion of pipes due to 
change of temperature, U bends made of steel pipe and having a 
radius of curvature not less than six times, and preferably ten times 
the diameter of the pipe, are preferred. Copper pipes cannot be rec¬ 
ommended for high pressures, while slip expansion joints are most 
undesirable on account of their liability to bind. 

Size. The size of steam pipes is determined by the velocity of 
flow. Probably an average velocity of 60 feet per second would be 
better than 100 feet per second, though in some cases where space 
is limited a vejocity as high as 150 feet per second has been used. 

Loss in Pressure. The loss in pressure in steam pipes may be 
obtained from the formula 

Q 2 wL 

V ~ V 2 ~~d>¥ 

where p i — p 2 is the loss in pressure in pounds per square inch; 
Q is the quantity of steam in cubic feet per minute; d is the diame¬ 
ter of pipe in inches; L is the length in* feet; w is the weight per 
cubic feet of steam at pressure p x and c is a constant, depending 
on size of pipe, values of which for the variation in the size of pipe 
are as follows: 


Diameter of pipe. 1" 2" 3" 4" 5" 6" 7" 8" 9" 10" 

Value of c. 36.8 45.3 52.7 56.1 57.8 58.4 59.5 60.1 60.7 61.2 61.8 

Diameter of pipe. 12" 14" 16" 18" 20" 22" 24" 

Value of c. 62.1 62.3 62.6 62.7 62.9 63.2 63.2 


Mounting. In mounting the steam pipe, it should be fastened 
rigidly at one point, preferably near the center of a long section, and 
allowed a slight motion longitudinally at all other supports. Such 
supports may be provided with rollers to allow for this motion, or 


383 








18 


POWER STATIONS 


the pipe may be suspended from wrought-iron rods which will give 
a flexible support. 

Location. Practice differs in the location of the steam piping, 
some engineers recommending that it be placed underneath the 
engine-room floor and others that it be located high above the engine- 
room floor. In any case it should be made easily accessible, and 
the valves should be located so that nothing will interfere with their 
operation. Proper provision must be made for draining the pipes. 

Lagging. All piping as well as joints should be carefully covered 
with a good quality of lagging as the amount of steam condensed 
in a bare pipe, especially if of any great length, is considerable. In 
selecting a lagging bear in mind that the covering for steam pipes 
should be incombustible, should present a smooth surface, should 
not be damaged easily by vibration or steam, and should have as 
large a resistance to the passage of heat as possible. It must not 
be too thick, otherwise the increased radiating surface will counter¬ 
balance the resistance to the passage of heat. 

The loss of power in steam pipes due to radiation is 

H = .262 rLd 

where H is loss of power in heat units; d is diameter of pipe in 
inches; L is the length of pipe in feet; and r is a constant depending 
on steam pressure and pipe covering, values of which for the varia¬ 
tions of these twc factors are as follows: 


Steam pressure in pounds (absolute) . 40 65 90 115 

Values of r for uncovered pipe. 437 555 620 684 

Value of r for pipe covered with 2 inches of 

hair felt. 48 58 66 73 


Referring to tables in books on boilers, the relative values of 
different materials used for covering steam pipes may be found. 

Superheated Steam. Superheated steam reduces condensation 
in the engines as well as in the piping, and increases the efficiency 
of the system. Its use was abandoned for several years, due to 
difficulties in lubricating and packing the engine cylinders, but by 
the use of mineral oils and metallic packing, these difficulties have 
been done away with to a large extent, while steam turbines are espe¬ 
cially adapted to the use of superheated steam. The application of 
heat directly to steam, as is done in the superheater, increases the 


384 





POWER STATIONS 


19 


TABLE IV 
Boiler Efficiencies 


Amount of Superheat 

Water Evaporated per Pound 
of Coal 

Without 

Superheat 

With Super¬ 
heat 

40 degrees F. 

7.82 

9.99 

42 degrees F. 

6.42 

7.06 

55 degrees F. 

6.00 

7.00 

56.5 degrees F. 

6.78 

8.66 

55.2 degrees F. 

7.15 

8.65 


efficiency of the boilers. Table IV shows the increase in boiler 
efficiency for a certain boiler test, the results being given in pounds 
of water changed to dry, saturated steam. Tests on various engines 
show a gain in efficiency as high as 9 per cent with a superheat of 
80° to 100° F., while special tests in some cases show even a greater 
gain. 

Superheaters are very simple, consisting of tubular boilers 
containing steam instead of water, and either located so as to utilize 
the heat of the gases, the same as economizers, or separately fired. 
They should be arranged so that they may be readily cut out of 
service, if necessary, and provision must be made for either flooding 
them or turning the hot gases into a by-pass, as the tubes would be 
injured by the heat if they contained neither water nor steam. Su¬ 
perheaters may be mounted in the furnace of the regular boiler set¬ 
ting or they may have furnaces of their own and be separately fired. 
For electrical stations using superheated steam the former type is 
usually employed and it has proved very satisfactory for moderate 
degrees of superheat. 

Feed Water. All water available for the feeding of boilers 
contain some impurities, among the most important of which as 
regards boilers are soluble salts of calcium and magnesium. Bicar¬ 
bonates of the alkaline earths cause precipitations on the interior 
of boilers, forming scale. Sulphate of lime is also deposited by 
concentration under pressure. Scale, when formed, not only de¬ 
creases the efficiency of the boiler but also causes deterioration, 
for if sufficiently thick, the diminished conducting power of the 
boiler allows the tubes or plates to be overheated and to crack or 


385 









20 


POWER STATIONS 


burst. Again, the scale may keep the water from contact with 
sections of the heated plates for some time and then, giving way, 
large volumes of steam are generated very quickly, and an explo¬ 
sion may result. 

Some processes to prevent the formation of scale are used, 
which affect the water after it enters the boilers, but they are not 
to be recommended, and any treatment the water receives should 
affect it previous to its being fed to the boilers. Carbonates and 

a small quantity of sulphate of 



lime may be removed by heat¬ 
ing in a separate vessel. Large 
quantities of sulphate of lime 
must be precipitated chemic¬ 
ally. 

Sediment must be removed 
by allowing the water to settle. 
Vegetable matters are some¬ 
times present, which cause a 
film to be deposited. Certain 
gases, in solution—such as oxy¬ 
gen, nitrogen, etc.—cause pit¬ 
ting of the boiler. This effect 
is neutralized by the addition 
of chemicals. Oil from the en¬ 
gine cylinder is particularly de¬ 
structive to boilers and when 
present in the condensed steam 
must be carefully removed. 
Feeding Appliances. Both 
feed pumps and injectors • are used for feeding the water to the 
boilers. Feed pumps may be either steam- or motor-driven. Steam- 
driven pumps are very inefficient, but they are simple and the speed 
is easily controlled. Motor-driven pumps are more efficient and 


Fig. 6. Feeding System for Boilers and 
’Pumps 


neater, but more expensive and more difficult to regulate efficiently 
over a wide range of speed. Direct-acting pumps may have feed- 
water heaters attached to them, thus increasing the efficiency of the 
apparatus as a whole. The supply of electrical energy must be 
constant if motor-driven pumps are to be used. 


386 


















POWER STATIONS 


21 


TABLE V 

Rate of Flow of Water, in Feet per Minute, Through Pipes of 
Various Sizes, for Varying Quantities of Flow 


Gallons 
per Min. 

\ IN. 

1 IN. 

11 IN. 

1* IN. 

2 0, 

IN. 

3 IN. 

4 IN. 

5 

218 

122 * 

00 

k»|H 

54 * 

© 

CO 

19* 

13* 

7f 

10 

436 

245 

157 

109 

61 

38 

27 

15* 

15 

653 

367| 

235.* 

163* 

91* 

58* 

40* 

23 

20 

872 

490 

314 

218 

122 

78 

54 

30 f 

25 

1090 

612* 

392* 

272* 

152* 

97* 

67* 

38* 

30 


735 

451 

327 

183 

117 

81 

46 

35 


857| 

549* 

381* 

213* 

136* 

94* 

53 f 

40 


980 

628 

436 

244 

156 

108 

61* 

45 


1102* 

706* 

490* 

274* 

175* 

121* 

69 

50 



785 

545 

305 

195 

135 

76* 

75 



1177* 

817* 

457* 

292* 

202* 

115 

100 




1090 

610 

380 

270 

153* 

125 





762* 

487* 

337* 

191* 

160 





915 

585 

405 

230 

175 





1067* 

682* 

472* 

268* 

200 





1220 

780 

540 

306t 


Feed pipes must be arranged so as to reduce the risk of fail¬ 
ure to a minimum, and for this reason they are almost always dupli¬ 
cated. More than one water supply is also recommended if there 
is the slightest danger of interruption on this account. One com¬ 
mon arrangement of feed-water apparatus is to install a few large 
pumps supplying either of two mains from which the boiler con¬ 
nections are taken. This is a complicated and costly system of 
piping. A scheme for feeding two boilers where each pump is capable 
of supplying both boilers is shown in Fig. 6. Pipes should be ample 
in cross-section, and, in long lengths, allowance must be made for 
expansion. ' Cast iron or cast steel is the material used for their con¬ 
struction; the joints being made by means of flanges fitted with 
rubber gaskets. 

The rate of flow of water in feet per minute through pipes of 
various sizes is given in Table V. A flow of 10 gallons per minute 
for each 100 h. p. of boiler equipment should be allowed without 
causing an excessive velocity of flow in the pipes—400 to 600 feet 
per minute represents a fair velocity. 


387 






















22 


POWER STATIONS 


Boiler Setting. The economical use of coal depends, to a large 
extent, on the setting of the boiler and proper dimensions of the 
furnaces. Internally-fired boilers require support only, while the 
setting of externally-fired boilers requires provision for the furnaces. 
Common brick, together with fire brick for the lining of portions 
exposed to the hot gases, are used almost invariably for boiler set¬ 
tings. It is customary to set the boiler units up in batteries of 
two, using a 20-inch wall at the sides and a 12-inch wall between 
the two boilers. The instructions for settings furnished by the 
manufacturers should be carefully followed out as they are based 
on conditions which give the best results in the operation of their 
boilers. 

Draft. The best ratio of heating to grate surface for boiler plants 
depends upon the kind of fuel used and the draft employed. Based 
on a draft of 0.5 inch of water, the following values are given for 
different grades of fuel: 

Pocahontas, W. Va., 45; Youghiogheny, Pa., 48; Hocking Valley, O., 45; 
Big Muddy, Ill., 50; Lackawanna, Pa., No. 1 buckwheat, 32. The first of 
these coals is semi-bituminous, the Lackawanna coal is anthracite, and the other 
coals are bituminous. 


Natural Draft . Natural draft is the most commonly used and 
is the most satisfactory under ordinary circumstances. In deter¬ 
mining the size of the chimney necessary to furnish this draft, the 
following formula is given by Kent: 


A = 


.06 F 

VT 


or h = 


m 1 


where A = area of chimney in sq. ft.; h = height of chimney in ft.; 
and F = pounds of coal per hour. 

The height of chimney should be assumed and the area calcu¬ 
lated, remembering that it is better to have the chimney too large 
than too small. 

The chimney may be either of brick or iron, the latter having 
a less first cost but requiring repairs at frequent intervals. Gen¬ 
eral rules for the design of a brick chimney may be given as follows: 

The external diameter of the base should not be less than is of the height 

Foundations must be of the best. 

Interiors should be of uniform section and lined with fire brick. 

An air space must exist between the lining and the chimney proper. 


388 




POWER STATIONS 


23 


The exterior should have a taper of from tV to I inch to the foot. 

Flues should be arranged symmetrically. 

Fig. 7 shows the construction of a brick chimney of good design, 
this chimney being used with 
boilers furnishing engines which 
develop 14,000 h. p. 

Mechanical Draft. Mechan¬ 
ical draft is a term which may 
be used to embrace both forced 
and induced draft. The first 
cost of mechanical-draft systems 
is less than that of a chimney, 
but the operation and repair are 
much more expensive and there 
is always the risk of break-down. 

Artificial draft has the advan¬ 
tage that it can be varied within 
large limits and it can be in¬ 
creased to any desired extent, 
thus allowing the use of low 
grades of coal. 

Firing of Boilers. Coal is 
used for fuel to a greater extent 
than any other material, though 
oil, gas, wood, etc., are used in 
some localities. Local condi¬ 
tions, such as availability, cost, 
etc., should determine the ma¬ 
terial to be used; no general 
rules can be given. From data 
regarding the relative heating 
values of different fuels we find : 

that 1 pound of petroleum, about {of a gallon, is equivalent, when 
used with boilers, to 1.8 pounds of coal and there is less deteriora¬ 
tion of the furnace with oil; that 7\ to 12 cubic feet of natural 
gas are required as the equivalent of 1 pound of coal, depending on 
the quality of the gas; that 2\ pounds of dry wood is assumed as the 
equivalent of 1 pound of coal. 



GROUND L/NE 


Fig. 7. Good Design of Brick Chimney 


389 























24 


POWER STATIONS 


Stoking. When coal is used, it requires stoking and this may he 
accomplished either by hand or by means of mechanical stokers, 
many forms of which are available. Mechanical stoking has the 
advantage over hand stoking in that the fuel may be fed to the 
furnace more uniformly, thus avoiding the subjection of the fires 
and boilers to sudden blasts of cold air as is the case when the fire 
doors are opened; in that a poorer grade of coal may be burned, 
if necessary; and in that the trouble .due to smoke is much reduced. 
It may be said that mechanical stokers are used almost universally 
in the more important electrical plants. Economic use of fuel requires 
great care in firing, especially if it is done by hand. 

Where gas is used, the firing may be made nearly automatic, 
and the same is true of oil firing, though the latter requires more 
complicated burners, as it is necessary that the oil be vaporized. 

In large stations, operated continuously, it is desirable that, 
as far as possible, all coal and ashes be handled by machinery, though 
the difference in cost of operation should be carefully considered 
before installing extensive coal-handling machinery. Machinery 
for automatically handling the coal will cost from $7.50 to $10 
per horse-power rating of boilers for installation, while the ash- 
handling machinery will cost from $1.50 to $3 per horse-power. 

The coal-handling devices usually consist of chain-operated 
conveyors which hoist the coal from railway, cars, barges, etc., to 
overhead bins from which it may be fed to the stokers. The ashes 
may be handled in a similar manner, by means of scraper con¬ 
veyors, or small cars may be used. Either steam or electricity may be 
used for driving this auxiliary apparatus. 

It is always desirable that there be generous provision for the 
storage of fuel sufficient to maintain operations of the plant over 
a temporary failure of supply. 

STEAM ENGINES 

The choice of steam prime movers is one which is governed 
by a number-of conditions which can be treated but briefly here. 
The first of these conditions relates to the speed of the engine to 
be used. There is considerable difference of opinion in regard to 
this as both high- and low-speed plants are in operation and are 
giving good satisfaction. Slow-speed engines have a higher first 


390 


POWER STATIONS 


25 


cost* and a higher economy. Probably in sizes up to 250 kw., the 
generator should be driven by high-speed engines; from 250 to 
500 kw., the selection of either type will give satisfaction; above 
500 indicated horse-power, the slow-speed type is to be recom¬ 
mended. Drop valves cannot be used with satisfaction for speeds 
above about 100 revolutions per minute, hence high-speed engines 
must use direct-driven valve gears, usually governed by shaft gov- 
. ernors. Corliss valves are used on nearly all slow-speed engines. 

The steam pressure used should be at least 125 pounds per 
square inch at the throttle and a pressure as high as 150 to 160 
pounds is to be preferred. 

Close regulation and uniform angular velocity are required 
for driving generators, especially alternators which are to operate 
in parallel. This means sensitive and active governors, carefully 
designed flywheels, and proper arrangement of cranks when more 
than one is used. 

High-speed engines should not have a speed change greater than 
1J per cent from no load to full load, but for prime movers used for 
driving large alternators operated in multiple, a speed change as 
great as 4 or 5 per cent may be desirable. The variation in angular 
velocity, where alternators are to be operated in parallel, should 
be within such limits that at no time will the rotating part be 
more than ^ of the pitch angle of two poles from the position 
it would occupy if the angular velocity were uniform at its mean 
value. 

For large engine-driven plants or plants of moderate size, com¬ 
pound condensing engines are almost universally installed. The 
advantage of these engines in increased economy are in part counter¬ 
balanced by higher first cost and increased complications, together 
with the pumps and added water supply necessary for the condensers. 
The approximate saving in amount of steam is shown in Table VI, 
which applies to a 500 horse-power unit. 

Triple expansion engines are seldom used for driving electrical 
machinery, as their advantages under variable loads are doubtful. 
Compound engines may be tandem or cross-compound and either 
horizontal or vertical. The use of cross-compound engines tends 
to produc' uniform angular velocity, but the cylinder should be so 
proportioned that the amount of work done by each is nearly equal. 


391 




26 


POWER STATIONS 


TABLE VI 


Engine 

Pounds of Steam 

per H. P. Hour 

Simple non-condensing 

30 

Simple condensing 

22 

Compound non-condensing 

24 

Compound condensing 

16 


A cylinder ratio of about to 1 will approximate average condi¬ 
tions. Either vertical or horizontal engines may be installed, each 
having its own peculiar advantages. Vertical engines require less 
floor space, while horizontal engines have a better arrangement of 
parts. Either type should be constructed with heavy parts and 
erected on solid foundations. 

Engines should preferably be direct-connected, but this is not 
always feasible, and gearing, belt, or rope drives must be resorted 
to. Countershafts, belt or rope driven, arranged with pulleys 
and belts for the different generators, and with suitable clutches, 
are largely used in small stations. They consume considerable 
power and the bearings require attention. 

Careful attention must be given to the lubrication of all running 
parts, and extensive oil systems are necessary in large plants. In 
such systems a continuous circulation of oil over the bearings and 
through the engine cylinders is maintained by means of oil pumps. 
After passing through the bearings, the machine oil goes to a properly 
arranged oil filter where it is cleaned and then pumped to the bear¬ 
ings again. A similar process is used in cylinder lubrication, the 
oil being collected from the exhaust steam, and only enough new 
oil is added to make up for the slight amount lost. The latter sys¬ 
tem is not installed as frequently as the continuous system for 
bearings. 

STEAM TURBINES 

Advantages. The steam turbine is now very extensively used 
as a prime mover for generators in power stations on account of its 
many advantages, some of which may be stated as follows: 

1. High steam economy at all loads. 

2. High steam economy with rapidly fluctuating loads. 


392 





POWER STATIONS # 


27 


3. Small floor space per kw. capacity, reducing to a minimum 

the cost of real estate and buildings. 

4. Uniform angular velocity, thus facilitating the parallel 

operation of alternators. 

5. Simplicity in operation and low expense for attendance. 

6. Freedom from vibration, hence low cost for foundations. 

7. Steam economy is not appreciably impaired by w T ear or lack 

of adjustment in long service. 

8. Adaptability to high steam pressures and high superheat 

without difficulty in operation and with consequent im¬ 
provement in economy. 

9. Condensed steam is kept entirely free from oil and can be 

returned to the boilers without passing through an oil 

separator. 

Types. The detailed descriptions of the different types of 
steam turbines are given in books devoted to steam engines and 
turbines and only a small amount of space can be devoted to them 
here. The first classification of steam turbines is into the impulse 
type and the reaction type of turbine. In the impulse type the 
steam is expanded in passing through suitable nozzles and does useful 
work in moving the blades of the rotating part by virtue of its kinetic 
energy. In the reaction type the steam is only partially expanded 
| before it comes into contact with the blades and much of the work 
i on the moving blades is accomplished by the further expansion of 
the steam and the reaction of the steam as it leaves the blades. Of' 
the impulse type the DeLaval and the Curtis turbines are well-known 
makes. The DeLaval turbine is built in small and moderate sizes 
only and is of the single-stage type. The Curtis turbine is built 
in all sizes up to the very largest and is of the multi-stage type. 
The Curtis turbine may be briefly described as follows: 

The Curtis turbine is divided into sections or stages, each 
stage containing one or more sets of stationary vanes and revolving 
buckets. These vanes and buckets are supplied with steam which 
passes through suitable nozzles to give it the proper expansion and 
velocity as it issues from the nozzles. By dividing the work into 
stages, the nozzle velocity of the steam is kept down to a moderate 
value in each stage and the energy of the steam is effectively given 
up to the rotating part without excessively high speeds. Fig. 8 


393 



28 


* POWER STATIONS 


shows the arrangement of nozzles, buckets, and stationary blades 
or guiding vanes for two stages. A complete turbine of the vertical 
type and of 5,000 kw. capacity is shown in Fig. 9. Governing is 
accomplished by automatically opening or closing some of the nozzles, 


-S ttfom £ 



A/to \s/r~>gr T9/o a'O-m 

lw««««t««t< S£o6/o/Ton/ iS/oo'ej 

5ioC/er>ony 
A/To i s/ngr J3 /orates 



A/ozzto TD/ojoZ-tr-oc/rn 


Mo\smej T3/OC/SS 


•Stod/onoru I 
fl/oc/e^ I 

/Kb s 




cccccccccccccccrcirrcrc 


aKKiccttcKfCffirff 


J> J»J> J) D)D D D DID D D M) 1) W¥5| 


Fig. 8. Diagram of Nozzles and Buckets in Curtis Steam Turbine 


and on overloads the steam may be automatically led directly into 
the second stage of the turbine. The step bearing which supports 
the weight of the rotating part may be lubricated by either oil or 
water under high pressure, this pressure being made great enough 
to support the weight of the moving element on a thin film of the 
lubricant. Only a vertical type of the Curtis turbine is shown here 
but it is also manufactured in the horizontal form. 


394 


| 
































ROWER STATIONS 


2M 

Of the reaction turbines the Parson’s type is the most prominent 
one. It is manufactured in the United States by the Westinghouse 
Machine Company and the Allis-Chalmers Company. An element¬ 
ary drawing of the cross-section of the Allis-Chalmers turbine is 
shown in Fig. 10. Steam enters this turbine at C through the gov¬ 
erning valve D, passes through the opening E, and thence expands 
in its passages through the series of revolving and stationary blades 



Fig. 9. Turbo-Alternator of 5,000 kw. Capacity 

in the three stages H, J, and K. The steam pressure is balanced 
by means of a series of disks or balance pistons shown at L, M, and 
N. The valve shown at V is automatically opened on overload, 
thus admitting steam directly into stage ./. 

The steam economy of the turbine increases with increase in 
vacuum approximately as follows: ’ For every increase in vacuum 
of one inch between 23 inches and 28 inches the increase in economy 
is 3 per cent for 100-kw. units, 4 per cent for 400-kw. units, and 
5 per cent for 1,000-kw. units. This is a greater improvement than 
can be obtained with steam engines under corresponding conditions 


395 


so 


POWER STATIONS 



396 


Fig. 10. Parson-Allis-Chalmers Turbine 






















































































POWER STATIONS 


31 


and the exhaust-steam or low-pressure turbine is being introduced 
to work in conjunction with the reciprocating steam engine, the 
steam expanding down to about atmospheric pressure in the engine 
and continuing down to a high vacuum through the low-pressure 
turbine. A receiver may be introduced between the engine and the 
turbine. A higher steam economy is claimed for such a combina¬ 
tion than could be secured by either engine or turbine alone. 


HYDRAULIC PLANTS 

Because of the relative ease with which electrical energy may 
be transmitted long distances, it has become quite common to locate 
large power stations where 
there is abundant water 
power, and to transmit the 
energy thus generated to 
localities where it is needed. 

This type of plant has been 
developed to the greatest 
extent in the western part 
of the United States, where 
in some cases the trans¬ 
mission lines are very exten¬ 
sive. The power houses now 
completed, or in the course 
of erection at Niagara Falls, 
are examples of the enor¬ 
mous size such stations may 
assume. 

Before deciding to util¬ 
ize water power for driving the machinery in central stations, the 
following points should be noted: 



Wdte y 


Fig. 11. Diagram of Reaction Turbines 


1. The amount of water power available. 

2. The possible demand for power. 

3. Cost of developing this power as compared with cost of plants using 
other sources of power. 

4. Cost of operation "compared with other plants and extent of trans¬ 
mission lines. 

Hydraulic plants are often much more expensive than steam 


397 




























32 


POWER STATIONS 


plants, but the first cost is more than made up by the saving in 
operating expenses. 

Methods for the development of water powers vary with the 
nature and the amount of the water supply, and they may be studied 
best by considering plants which are in successful operation, each 
one of which has been a special problem in itself. A full descrip¬ 
tion of such plants would be too extensive to be incorporated here, 
but they can be found in the various technical journals. 

Water Turbines. Water turbines used for driving generators 
are of two general classes, reaction turbines and impulse turbines. 



Fig. 12. Pelton Type of Impulse Turbine 


Reaction .turbines may be subdivided into parallel-flow, outward- 
flow, and inward-flow types. Parallel-flow turbines are suited for low 
falls, not exceeding 30 feet. Their efficiency is from 70 to 72 per 
cent. Outward-flow and inward-flow turbines give an efficiency 
from 79 to 88 per cent. Impulse turbines are suitable for very high 
falls and should be used from heads exceeding, say, 100 feet, though 
it is difficult to sav at what head the reaction turbine would give 
place to the impulse wheel, as reaction turbines are giving good 
satisfaction on heads in the neighborhood of 200 feet, while impulse 
wheels are operated with falls of but 80 feet. A reaction wheel is 
shown in Fig. 11, and the Pelton wheel, one of the best known types 


398 

























POWER STATIONS 33 


TABLE VII 
Pressure of Water 


Feet 

Head 

Pressure 
Pounds per 
Sq. In. 

Feet 

Head 

Pressure 
Pounds per 
Sq. In. 

Feet 

Head 

Pressure 
Pounds per 
Sq. In. 

Feet 

Head 

Pressure 
Pounds per 
Sq. In. 

10 

4.33 

105 

45.48 

200 

86.63 

295 

127.78 

15 

6.49 

no 

47.64 

205 

* 88.80 

300 

129.95 

20 

8.66 

115 

49.81 

210 

90.96 

310 

134.28 

25 

10.82 

120 

51.98 

215 

93.13 

320 

138.62 

30 

12.99 

125 

54.15 

220 

95.30 

330 

142.95 

35 

15.16 

130 

56.31 

225 

97.46 

340 

147.28 

40 

17.32 

135 

58.48 

230 

99.63 

350 

151.61 

45 

19.49 

140 

60.64 

235 

101.79 

360 

155.94 

50 

21.65 

145 

62.81 

240 

103.90 

370 

160.27 

55 

23.82 

150 

64.97 

245 

106.13 

380 

164.61 

60 

25.99 

155 

67.14 

250 

108.29 

390 

168.94 

65 

28.15 

160 

69.31 

255 

110.46 

400 

173.27 

70 

30.32 

165 

71.47 

260 

112.62 

500 

216.58 

75 

32.48 

170 

73.64 

265 

114.79 

600 

259.90 

80 

34.65 

175 

75.80 

270 

116.96 

700 

303.22 

85 

36.82 

180 

77.97 

275 

119.12 

800 

346.54 

90 

38.98 

185 

80.14 

280 

121.29 

900 

389.86 

95 

41.15 

190 

82.30 

285 

123.45 

1000 

433.18 

100 

43.31 

195 

84.47 

290 

125.62 




of impulse wheels, is shown in Fig. 12. An efficiency as high as 
86 per cent is claimed for the impulse wheel under favorable con¬ 
ditions. The fore bay leading to the flume should be made of such 
size that the velocity of. water does not exceed 1| feet per second; 
and it should be free from abrupt turns. The same applies to the 
tailrace. The velocity of water in wooden flumes should hot exceed 
7 to 8 feet per second. Riveted steel pipe is used for the penstocks 
and for carrying water from considerable distances under high heads. 
In some locations it is buried, in others it is simply placed on the 
ground. Wooden-stave pipe is used to a large extent w T hen the 
heads do not much exceed 200 feet. In Table VII is given the 
pressure of water in pounds per square inch at different heads, 
while in Table VIII is given considerable data relating to riveted- 
steel hydraulic pipe. Governors of the usual types are required 
to keep the speed of the turbine constant under change of load and 
change of head. 


399 
















POWER STATIONS 

TABLE VII! 


Riveted Hydraulic Pipe 


Diam. of 
Pipe in 
Inches 

Area of Pipe 
in Square 
Inches 

Thickness of 
Iron by 
Wire Gauge 

Head in Feet 
the Pipe, will 
Safely Stand 

Cu. Ft. Water 
Pipe will Con¬ 
vey per Min . 
at Vel. 3 Ft. 
per Sec. 

Weight per 
Lineal Foot 
in Pounds 

3 

7 

18 

400 

9 

2 

4 

12 

18 

350 

16 

2% 

4 

12 

16 

525 

16 

3 

5 

20 

18 

325 

25 

3% 

5 

20 

16 

' 500 

25 

4 % 

5 

20 

14 

675 

25 

5 

6 

28 

18 

296 

36 

4% 

6 

28 

16 

487 

36 

5% 

6 

28 

14 

743 

36 

7% 

7 

38 

18 

254 

50 

5% 

7 

38 

16 

419 

50 

6% 

7 

38 

14 

640 

50 

8% 

' 8 

50 

16 

367 

63 

7V 2 

8 

50 

14 

560 

63 

9 % 

8 

50 

12 

854 ■ 

63 

13 

9 

63 

16 

327 

80 

s% 

9 

63 

14 

499 

80 

10% 

9 

63 

12 

761 

80 

14% 

10 

78 

16 

295 

100 

9% 

10 

78 

14 

450 

100 

n% 

10. 

78 

12 

687 

100 

15% 

10 

78 

11 

754 

100 

17 X 

10 

78 

10 

900 

100 

19% 

11 

95 

16 

269 

120 

9% 

11 

95 

14 

412 

120 

13 

11 

95 

12 

626 

120 

17 X. 

11 

95 

11 

687 

120 

18% 

11 

95 

10 

820 

120 

21 

12 

113 

16 

246 

142 

11% 

12 

113 

14 

377 

142 

14 

12 

113 

12 

574 

142 

18% 

12 

113 

11 

630 

142 

19% 

12 

113 

10 

753 

142 

22% 

13 

132 

16 

228 

170 

12 

13 

132 

14 

348 

170 

15 

13 

132 

12 

530 

170 

20 

13 

132 

11 

583 

170 

22 

13 

132 

10 

696 

170 

24% 

14 

153 

16 

211 

200 

13 

14 

153 

14 

324 

200 

16 

14 

153 

12 

494 

200 

21% 

14 

153 

11 

543 

200 

23% 

14 

153 

10 

648 

200 

26 

15 

176 

16 

197 

225 

13% 

15 

176 

14 

302 

225 

17 

15 

176 

12 

460 

225 

23 

15 

176 

11 

507 

225 

24% 

15 

176 

10 

606 

225 

28 

16 

201 

16 

185 

255 

14% 

16 

201 

14 

283 

255 

17% 

16 

201 

12 

432 

255 

24% 

16 

201 

11 

474 

255 

26% 

16 

201 

10 

567 

255 

29% 


400 


■ 






















POWER STATIONS 


35 


Riveted Hydraulic Pipe 


(Continued) 


Diam. of 
Pipe in 
Inches 

Area of Pipe 
in Square 
Inches 

Thickness of 
Iron by 
Wire Gauge 

Head in Feet 
the Pipe will 
Safely Stand 

Cu. Ft. Water 
Pipe wall Con¬ 
vey per Min. 
at Vel. 3 Ft. 
per Sec. 

Weight per 
Lineal Foot 
in Pounds 

18 

254 

16 

165 

320 

16% 

18 

254 

14 

252 

320 

20% 

18 

254 

12 

385 

320 

27 y 

18 

254 

11 

424 

320 

30 

18 

254 

10 

505 

320 

34 

20 

314 

16 

148 

400 

18 

20 

314 

14 

227 

400 

22 % 

20 

314 

12 

346 

400 

30 

20 

314 

11 

380 

400 

32% 

20 

314 

10 

456 

400 

36% 

22 

380 

16 

135 

480 

20 

22 

380 

14 

206 

480 

24 % 

22 

380 

12 

316 

480 

32% 

22 

380 

11 

347 

. 480 

35% 

22 

380 

. 10 

415 

480 

40 

24 

452 

14 

188 

570 

27% 

24 

452 

12 

290 

570 

35% 

24 

452 

11 

318 

570 

39 

24 

452 

10 

379 

570 

43% 

24 

452 

8 

466 

570 

53 

26 

530 

14 

175 

• 670 

29% 

26 

530 

12 

267 

670 

38% 

26 

530 

11 

294 

670 

42 

26 

530 

10 

352 

670 

37 

26 

530 

8 

432 

670 

57% 

28 

615 

14 

102 

775 

31% 

28 

615 

12 

247 

775 

41% 

28 

615 

11 

273 

775 

45 

28 

615 

10 

327 

775 

50% 

28 

615 

8 

400 

775 

61% 

30 

706 

12 

231 

890 

44 

30 

706 

11 

254 

890 

48 

30 

706 

10 

304 

890 

54 

30 

706 

8 

375 

890 

65 

30 

706 

7 

425 

890 

74 

36 

1017 

11 

141 

1300 

58 

36 

1017 

10 

155 

1300 

67 

36 

1017 

8 

192 

1300 

78 

36 

1017 

7 

210 

1300 

88 

40 

1256 

10 

141 

1600 

71 

40 

1256 

8 

174 

1600 

86 

40 

1256 

7 

189 

1600 

97 

40 

1256 

6 

213 

1600 

108 

40 

1256 

4 

250 

1600 

126 

42 

1385 

10 

135 

1760 

74% 

42 

1385 

8 

165 

1760 

91 

42 

1385 

7 

180 

1760 

102 

42 

1385 

6 

210 

1760 

114 

42 

1385 

4 

240 

1760 

133 

42 

1385 

% 

270 

1760 

137 

42 

1385 

3 

300 

1760 

145 

42 

1385 

5 

16 

321 

1760 

177 

42 

1385 

H 

363 

1760 

216 


• 401 















36 


POWER STATIONS 


TABLE LX 

Horse-Power per Cubic Foot of Water per Minute for Different Heads 


Heads 

in 

Feet 

Horse- 

Power 

Heads 

in 

Feet 

Horse- 

Power 

Heads 

in 

Feet 

Horse- • 
Power 

Heads 

in 

Feet 

Horse- 

Power 

1 

.0016098 

170 

.273666 

330 

.531234 

490 

.788802 

20 

.032196 

180 

.289764 

340 

.547332 

500 

.804900 

30 

.048294 

190 

.305862 

350 

.563430 

520 

.837096 

40 

.064392 

200 

.321960 

360 

.579528 

540 

.869292 

50 

.080490 

210 

.338058 

370 

.595626 

560 

.901488 

60 

.096588 

220 

.354156 

380 

.611724 

580 

.933684 

70 

.112686 

230 

.370254 

390 

.627822 

600 

.965880 

80 

.128784 , 

240 

.386352 

400 

.643920 

650 

1.046370 

90 

.144892 

250 

.402450 

410 

.660018 

700 

1.126860 

100 

.160980 

260 

.418548 

420 

.676116 

750 

1.207350 

110 

.177078 

270 

.434646 

430 

.692214 

800 

1.287840 

120 

.193176 

280 

.450744 

440 

.708312 

900 

1.448820 

130 

.209274 

290 

.466842 

450 

.724410 

1000 

1.609800 

140 

.225372 

300 

.482940 

460 

.740508 

1100 

1.770780 

150 

.241470 

310 

.499038 

470 

.756606 



160 

.257568 

320 

.515136 

480 

.772704 




GAS PLANT 

The gas engine using natural gas, producer gas, blast furnace 
gas, or even illuminating gas in some instances, is being used to a 
considerable extent as a prime mover for electric generators. The 
advantages claimed for the gas engine are: 

1. Minimum fuel and heat consumption. 

2. Low cost of operation and maintenance. 

3. Simplification of equipment and small number of auxiliaries. 

4. No heat lost due to radiation when engines are idle. 

5. Quick starting. 

6. Extensions may be easily made. 

7. High pressures are limited to the engine cylinders. 

As disadvantages of the gas engine may be mentioned the large floor 
space required; small overload capacity; and the heavy and expensive 
foundations necessary. 

Fig. 13 shows the efficiency and amount of gas consumed by 
a 500-h. p. engine, Pittsburg natural gas being used. 


402 


















POWER STATIONS 


37 


The only auxiliaries needed where natural gas is employed are 
the igniter generators and the air compressors—with a pump for the 
jacket water in some cases which may be driven by either a motor 
or a separate gas engine. The'jacket water may be utilized for heat¬ 
ing purposes in many plants. Cooling towers may be installed 
where water is scarce. 

Parallel operation of alternators when direct-driven by gas 
engines has been successful, a spring coupling being used between 



Fig. 13. Efficiency Curves of a 500-H. P. Gas Engine 

the engines and the generators in some cases to absorb the variation 
in angular velocity. 

The overload capacity of gas engines depends upon the man¬ 
ner of rating. The ultimate capacity is reached when the engine 
is using a full charge of the best mixture of gas and air at each power 
stroke. Many manufacturers rate their engines at 10 per cent 
below the maximum capacity, thus allowing for a limited amount 
of overload. The gas consumption of gas engines is relatively high 
at loads less than 50 per cent of normal; hence, it is desirable that the 
load be fairly constant and at some value between 50 and 100 per 
cent of the rating of the machine. H. G. Stott has proposed that 
the gas engine be combined with the steam turbine in some electrical 


403 




























































38 


POWER STATIONS 


plants, since the turbine can carry heavy overloads and is fairly 
economical on all loads. In such a plant the steam turbine would 
carry the fluctuations, and arrangements would be made so that the 
gas engine would carry a nearly constant load. 

Gas-producers for gas engines are of two types: the suction 
producer, used for small plants and employing high-grade fuels; 
and the pressure producer, used for the larger units and manufac¬ 
tured for all grades of fuel. 

The fact that no losses occur, due to heat radiation when the 
machines are not running, and the lack of losses in piping, add 
greatly to the plant efficiency. If producer gas or blast-furnace 
gas is used, a larger engine must be installed to give the same power 
than when natural or ordinary coal gas is used. Electric stations 
are often combined with gas works, and gas engines can be installed 
in such stations to particular advantage in many cases. 

In addition to the gas engine, other forms of internal com¬ 
bustion engines, such as oil engines and gasoline engines, are being 
used to a limited extent in small stations. 

ELECTRIC PLANT 
GENERATORS 

The first thing to be considered in the electric plant is the 
generators, after which the auxiliary apparatus in the way of ex¬ 
citers, controlling switches, safety devices, etc., will be taken up. 
A general rule which, by the way, applies to almost all machinery for 
power stations, is to select apparatus which is considered as “stand¬ 
ard” by the manufacturing companies. This rule should be fol¬ 
lowed for two reasons: First, reliable companies employ men who 
may be considered as experts in the design of their machines, and 
their best designs are the ones which are standardized. Second , 
standard apparatus is from 15 to 25 per cent cheaper than semi¬ 
standard or special work, owing to larger production, and it can be 
furnished on much shorter notice. Again, repair parts are more 
cheaply and readily obtained. 

Specifications should call for performance, and details should 
be left, to a very large extent, to the manufacturers. Following 
are some of the matters which may be incorporated in the specifi¬ 
cations for generators: 


404 





POWER STATIONS 


39 


1. Type and general characteristics. 

2. Capacity and overload with heating limits. 

3. Commercial efficiency at various loads. 

4. Excitation. 

5. Speed and regulation. 

6. Mechanical features. 

Types. The type of machine will be determined by the sys¬ 
tem selected. Generators may be direct-current or alternating- 
current—single or polyphase—or as in some plants now in operation, 
they may be double-current. The voltage, compounding, frequency, 
etc., should be stated. Direct-current machines are seldom wound 
! for a voltage above 600, but alternating-current generators may 
' be purchased which will give as high as 15,000 volts at the terminals. 
As a rule it is well not to use an extremely high voltage for the 
generators themselves, but to use step-up transformers in case a 
very high line voltage is necessary. Up to about 7,000 volts, gen¬ 
erators may be safely used directly on the line. Above this, local 
conditions will decide whether to connect the machine directly to 
the line or to step up the voltage. Machines wound for high potential 
are more expensive for the same capacity and efficiency, but the 
cost of step-up transformers and the losses in the same are saved 
by using such machines, so that there is a slight gain in efficiency 
which may be utilized in better regulation of the system, or in lighter 
construction of the line. On the other hand, lightning troubles are 
liable to be aggravated when transformers are not used, as the 
transformers act as additional protection to the machines, and if the 
transformers are injured they may be more readily repaired or 
replaced. 

The following voltages are considered standard: Direct-current 
generators 125, 250, 550-600. Alternating-current systems, high 
pressure, 2,200, 6,600, 11,000, 22,000, 33,000, 44,000, 66,000, 88,000, 
and 110,000. The generators, when used with transformers, should 
be capable of giving a no-load voltage 10 per cent in excess of these 
figures. Twenty-five and 60 cycles are considered as standard fre¬ 
quencies, the former being more desirable for railway work and the 
latter for lighting purposes. 

Capacity. The size of machines to be chosen has been briefly 
considered. Alternators are rated for non-inductive load or a power 


405 


40 


POWER STATIONS 


% TABLE X 

Average Maximum Efficiencies 


Kw. 

Per Cent 

Kw. 

Per Cent 

5 

85 

150 

93 

10 

88 

200 

94 

25 

90 

500 

95 

50 

92 

1000 

96 


factor of unity unless a different power factor is distinctly stated. 
Aside from the overload capacity to be counted upon as reserve, 
the Standardization Report of the American Institute of Electrical 
Engineers recommends the following for the heating limits and 
overload capacity of generators: 

Maximum Values of Temperature Elevation 
Field and armature, by resistance, 50 o 

Commutator and collector rings and brushes, by thermometer, 55© C. 
Bearings and other parts of machine, by thermometer, 40° C. 

Overload capacity should be 25 per cent for two hours, with 
a temperature rise not to exceed 15 degrees above full load values, 
the machine to be at constant temperature reached under normal 
load, before the overload is applied. A momentary overload of 
50 per cent should be permissible without excessive sparking or 
injury. Some companies recommend an overload capacity of 50 
per cent for two hours when the machines are to be used for railway 
purposes. The above temperature increases are based upon a room- 
temperature of 25° C. 

Efficiency. As a rule, generators should have a high efficiency 
over a considerable range of load, although much depends upon 
the nature of the load. It is always desirable that maximum 
efficiency be as high as is compatible with economic investment. 

lable X gives reasonable efficiencies which may be expected 
for generating apparatus. In order to arrive at what may be con¬ 
sidered the best maximum efficiency to be chosen, the cost of power 
generation must be known, or estimated, and the fixed charges on 
capital invested must also be a known quantity. From the cost 
of power, the saving on each per cent increase in efficiency can be 
determined, and this should be compared with the charges on the 


406 









POWER STATIONS 


41 


TABLE XI 

Exciters for Single-Phase Alternating-Current Generators 

60 Cycles 


Alternator Classificaton 

Exciter Classific 

ATION 

Poles 

Kw. 

Speed 

Poles 

Kw. 

Speed 

8 

60 

900 

2 

1.5 

1,900 

8 

90 

900 

2 

1.5 

1 900 

8 

120 

900 

2 

1.5 

1 900 

12 

180 

600 

2 

2.5 

1,900 

16 

300 

450 

2 

4.5 

1,800 


additional investment necessary to secure this increased efficiency. 
A certain point will be found where the sum of the two will be a 
minimum. 

If a generator is to be run for a considerable time at light loads, 
one with low “no-load” losses should be chosen. These losses are 
not rigidly fixed but they vary slightly with change of load. It is 
the same question of “all-day efficiency” which is treated, in the 
case of transformers, in “Power Transmission.” Under no-load 
losses may be considered, in shunt-wound generators, friction losses, 
core losses, and shunt-field losses. I 2 R losses in the series field, in 
the armature, and in the brushes, vary as the square of the load. 

Excitation. Dynamos, if for direct current, may be self-excited, 
shunt-wound, compound-wound, or separately excited. Separate 
excitation is not recommended for these machines. Alternators 
require separate excitation, though they may be compounded by 
using a portion of the armature current when rectified by a commu¬ 
tator. Automatic regulation of voltage is always desirable, hence, the 
general use of compound-wound machines for direct currents. Many 
alternators using rectified currents in series fields for keeping the 
voltage nearly constant are in service in small plants, as well as 
several of the so-called “compensated” alternators, arranged with 
special devices which maintain the same compounding with different 
power factors. The latter machine gives good satisfaction if properly 
cared for, but an automatic regulator, governed by the generator 
voltage and current, which acts directly on the exciter field, is taking 
its place. This regulator, known as the Tirrill regulator, is de¬ 
scribed under “Power Transmission.” The capacity of the exciters 


407 












42 


POWER STATIONS 


must be such that they will furnish sufficient excitation to maintain 
normal voltage at the terminals of the generators when running at 
50 per cent overload. Table XI gives the proper capacity of exciters 
for the generators listed. On account of the fact that the speed at 
which the unit runs is an important factor in the excitation required, 
no general figure can be given. 

Exciters may be either direct-connected or belted to the shaft 
of the machine which they excite, or they may be separately driven. 

•They are usually compound- 
wound and furnish current at 
125 or 250 volts. Separately- 
driven exciters are preferred for 
most plants as they furnish a 
more flexible system, and any 
drop in the speed of the gen¬ 
erator does not affect the ex¬ 
citer voltage. Ample reserve 
capacity of exciters should be 
installed, and in some cases 
storage batteries, used in con¬ 
junction with exciters, are rec¬ 
ommended in order to insure 
reliability of service. 

Speed and Regulation. If 
direct-connected, the speeds of the generators will be determined by 
the prime mover selected. If belt-driven, small machines may be run 
at a high speed, as high-speed machines are cheaper than slow- or 
moderate-speed generators. In large sizes, this saving is not so great. 

When shunt-wound dynamos are used, the inherent regula¬ 
tion should not exceed 2 to 3 per cent for large machines. For alterna¬ 
tors, this is much greater and depends on the power factor of the 
load. A fair value for the regulation of alternators on non-inductive 
load is 10 per cent. 

Mechanical Features. Motor-generator sets, boosters, frequency 
changers, and other rotating devices come irtider the .head of special 
apparatus and are governed by the same general rules as generators. 

Transformers. Transformers for stepping the voltage from 
that generated by the machine up to the desired line voltage, or 



Fig. 14. Air-Cooled Transformer 


408 



















































POWER STATIONS 


43 


vice versd, at the substation, may be of three general types, accord¬ 
ing to the method of cooling. Large transformers require artificial 
means of cooling, if they are not to be too bulky and expensive. They 
may be air-cooled, oil-cooled, or water-cooled. 



Fig. 15. Oil-Cooled Transformer 


Air-cooled transformers, Fig. 14, are usually mounted over an 
air-tight pit fitted with one or more motor-driven blowers which feed 
into the pit. The transformer coils are subdivided so that no part 
of the winding is at a great distance from air and the iron is pro¬ 
vided with ducts. Separate dampers control the amount of air 
which passes between the coils or through the iron. Such trans¬ 
formers give good satisfaction for voltages up to 20,000 or higher, 
and can be built for any capacity. Care must be taken to see that 


409 














44 


POWER STATIONS 


there is no liability of the air supply failing, as the capacity of the 
transformers is greatly reduced when not supplied with air. 



Fig. 16. Water-Cooled Transformer 


Oil-cooled transformers, big. 15, have their cores and windings 
placed in a large tank filled with oil. The oil serves to conduct the 
heat to the case, and the case is usually made either of corrugated 
sheet metal or of cast iron containing deep grooves, so as to increase 
the radiating surface. These transformers do not require such heavy 










POWER STATIONS 


45 


insulation on the outside of the coils as air-blast machines because 
the oil serves this purpose. Simple oil-cooled transformers are 
seldom built for capacities exceeding 250 kw. as they become too 
bulky, but they are employed for the highest voltages now in use. 



Fig. 17. 400-Kw. Water-Cooled Oil Transformer 


Water-cooled transformers , Figs. 16 and 17, are used when high 
voltages are required. This type is like an oil-cooled transformer, but 
with water tubes arranged in coils in the top. Cold water passes 
through these tubes and aids in removing heat from the oil. Some 
types have the low-tension windings made up of tubes through which 
the water circulates. Water-cooled transformers must not have 
the supply of cooling water shut off for any length of time when 
under normal load or they will overheat. 


411 





46 


POWER STATIONS 


One or more spare transformers should always be on hand and 
they should be arranged so that they can be put into service on 
very short notice. 



r r " —11-=!-^ 


X ( *—l. o 

fret# 

nA - 

Rcmi 


Fig. 18. Three-Phase Air-Blast Transformers. Total Capacity, 3,000 Kw. 


Three-phase transformers allow a considerable saving in floor 
space, as shown by a comparison of the machines in Figs. 18 and 


■ u 

• H 

■ H 




X, ^ X 




XL U 

XL l 

rin 

XL l 

) XL l 

) XL l 

1 XL i 

1 XL i 



Fig. 19. Single-Phase Air-Blast Transformers. Total Capacity, 3,000 Kw. 


19. They are cheaper than three separate transformers which make 
up the same capacity, but they are not as flexible as a single-phase 
transformer and one complete unit must be held for a reserve or 
“spare” transformer. 

Storage Batteries. The use of storage batteries for central 
stations and substations is clearly outlined in “Storage Batteries.” 


412 























































































































































































































POWER STATIONS 


4-7 


The chief points of advantage are: 

1. Reduction in fuel consumption due to the generating machinery 
being run at its greatest economy. 

2. Better voltage regulation. 

3. Increased reserve capacity and less liability to interruption of service. 

The main disadvantage is the high first cost and depreciation. 

SWITCHBOARDS 

The switchboard is the most vital part of the whole system of 
supply, and should receive consideration as such. Its objects are: to 
collect the energy as supplied by the generators and to direct it to 
the desired feeders, either overhead or underground; to furnish a 
support for the various measuring instruments connected in service, 
as well as the safety devices for the protection of the generating ap¬ 
paratus; and to control the pressure of the supply. Some of the 
essential features of all switchboards are: 

1. The apparatus and supports must be fire-proof. 

2. The conducting parts must not overheat. 

3. Parts must be easily accessible. 

4. Live parts except for low potentials must not be placed on the front 
of the operating panels. 

5. The arrangement of circuits must be symmetrical and as simple 
as it is convenient to make them. 

6. Apparatus must be arranged so that it is impossible to make a wrong 
connection that would lead to serious results. 

7. It should be arranged so that extensions may be readily made. 

There are two general types—in the first, all of the switching 
and indicating apparatus is mounted directly on panels; and in the 
second, the current-carrying parts are at some distance from the 
panels, the switches being controlled by long connecting rods, or else 
operated electrically or by means of compressed air. The first may 
again be divided into direct-current and alternating-current switch¬ 
boards. It is from the first class of apparatus that the switchboard 
gets its name and the term is still applied, even when the board 
proper forms the smallest part of the equipment. The term “switch- 
gear” is now being introduced to cover all of the apparatus con¬ 
nected with the switching operations and the term “switchboard” is 
being reserved for the panels and their apparatus only. Switchboards 
have been standardized to the extent that standard generator, ex¬ 
citer, feeder, and motor panels may be purchased for certain classes 


413 



48 


POWER STATIONS 


lA/ijaeot (Joint 



A therene Soap stone. 
On lA/ooct 



Extra /nsuiation 


JC= 3 ssa *■ 2 JS y + -s». 30C 


Three-Conductor Cable Without Joints 
Wiped. Joint /nsuiation- 


Aiberene Soapstone 
Or Wood 




Extra /nsuiation 

x-sjsa +£jjy+4 3oL 


Three-Conductor Cable With Joints 



Two-Conductor Cable With Joints 



Single-Conductor Cable With Joints 


VOLTS 

A 

B 

C 

D 

E 

F 

6,600 

1 

12 

5 

i 

8 

Ol 

1 

13,200 

U 

15 

8 

1 

4 

4 

2 

26,400 

2 

19 

14 

1 

2 

7 

4 


i-inch Lead or T Vmch Brass Bells 


Fig. 20. Part Section—Showing Cable Bells in Place 


414 



































































































































POWER STATIONS 49 

of work, but the vast majority of them are made up as semi-standard 
or special. 

The leads which carry the current from the machines to the 
switches should be put in with very careful consideration. Their 
size should be such that they will not heat excessively when carry¬ 
ing the rated overload of the machine, and they should preferably 
be placed in fire-proof ducts, although low-potential leads do not 
always require this construction. Curves showing sizes for lead- 
covered cables for different currents are given in ‘Tower Trans¬ 
mission.” Table XII gives standard sizes of wires and cables to¬ 
gether with the thickness of insulation necessary for different voltages. 
Cables should be kept separate as far as possible so that if a fault 
does occur on one cable, neighboring conductors will not be injured. 
For lamp and instrument wiring, such as leads to potential and 
current transformers, the following sizes of wire are recommended: 
No. 16 or No. 14, wiring to lamp sockets. 

No. 12 wire, rubber insulation, all other small wiring under 600 volts po¬ 
tential. 

No. 12, rubber insulation for primaries of potential transformers from 
600 to 3,500 volts. 

No. 8, Y2" rubber insulation for primaries of potential transformers up to 
6,600 volts. 

No. 8, rubber insulation for primaries of potential transformers up to 
10,000 volts. 

No. 4, ||" rubber insulation for primaries of potential transformers up to 
15,000 volts. 

No. 4, If" rubber insulation for primaries of potential transformers up to 
20,000 volts. 

No. 4, It" rubber insulation for primaries of potential transformers up to 
25,000 volts. 

Where high-tension cables leave their metallic shields they 
are liable to puncture, so that the sheath should be flared out at this 
point and the insulation increased by the addition of compound. 
Fig. 20 shows such cable bells, as they are called, as are recommended 
by the General Electric Company. Other types of cable outlets are 
introduced from time to time. A very excellent type makes use of 
porcelain sleeve for each conductor at the point when it leaves the 
lead sheath. 

Panels. Central-station switchboards are usually constructed 
of panels about 90 inches high, from 16 inches to 36 inches wide, and 
i\ inches to 2 inches thick. Such panels are made of blue Vermont, 


415 



50 


POWER STATIONS 


TABLE XII 

Standard Wire 

(Solid) 


Area 

Diameter 

Terminal 

Amperes 

Thickness 

OF 

Rubber Insulation 

Gauge 

Inches 

Drilling 

Volts 

Circular 

Mils 

Bare 

Drill 

Number 

Constant 

Current 

Capacity 

O 

O 

3,500 

6,600 

O 

O 

o 

o 

y—4 

15,000 

O 

o 

o 

o 

CM 

25,000 

B. & S . 

2,582 

.051 

30 

4 









16 1 

4,106 

.064 

30 

6 

3 

64 








14 

6,530 

.081 

30 

10 

3 

64 

3 

32 







12 

16,510 

.128 

18 

25 

3 

64 

3 

32 

5 

32 


7 

32 




8 

26,251 

.162 

5 

40 

1 

16 








6 

41,743 

.204 

i 

4 

60 

1 

16 

3 

32 

5 

32 


7 

32 

2 1 

6? 

1 4 

3 2 

1 7 
32 

4 

66,373 

.257 

/ 5 

T6 

90 

1 

16 








2 

83,695 

.289 

11 

32 

110 

5 

64 








1 

105,593 

.325 

3 

8 

130 

5 

64 

3 

32 

5 

32 


7 

32 

2 1 

64 

1 4 

3 2 

1 7 
32 

0 

133,079 

.365 

7 

16 

170 

5 

64 








00 

167,805 

.410 

1 5 

32 

205 

5 

64 








000 

211,600 

.460 

1 7 

32 

250 

5 

64 

3 

32 

5 

32 


7 

32 

64 

14 

3 2 

17 

32 

0000 


Standard Cable 

(Stranded) 


Circular 

Mils 

Diameter, 

Terminal 

Con. Cur. 

Thickness of Rubber 

Inches 

Drilling 

Capacity 

Insulation 

Bare 

Inches 

Amperes 

(For 6000 V. only ) 

250,000 

.568 

5 . 

8 

290 

3 

32 

300,000 

.637 

23 

32 

240 

3 

32 

350,000 

.680 

3 

4 

380 

3 

32 

400,000 

.735 

1 3 

1 6 

420 

3 

32 

500,000 

.820 

29 

32 

500 

3 

32 

600,000 

.900 

1 

575 

7 

64 

800,000 

1.037 

1* 

710 

7 

64 

1,000,000 

1.157 

H 

830 

7 

64 

1,500,000 

1.412 

li 

1100 

1 

8 

2,000,000 

1.65 

if 

1350 

i 

8 


pink Tennessee, or white Italian marble, or of black enameled or 
oiled slate. Slate is not recommended for voltages exceeding 1,100. 
1 he panels are made in two or three parts. When made in two parts, 
the sub-base is from 24 to 28 inches high. They are polished on the 
front and the edges are beveled. Angle and tee bars or pipe work, 
together with foot irons and tie rods, form the supports for such 
panels, and on these panels are mounted the instruments, main 


416 





































POWER STATIONS 


51 


switches, or controlling apparatus for the main switches, as the case 
may be, together with relays and hand wheels for rheostats and 
regulators. 

The usual arrangement of the panels is to have a separate 
panel for each generator, exciter, and feeder, together with what is 
known as a station or total- 



output panel. In order to 
facilitate extensions and 
simplify connections, the 
feeder panels are located 
at one end of the board, the 
generator panels are placed 
at the other end, and the 
total-output panel occupies 
a position between the two. 

The main bus bars extend 
throughout the length of 
the generator and feeder 
panels, and the desired con¬ 
nections are readily made. 

The instruments required 

are very numerous. Lists of meters required for standard practice 
and regular panels are given later. 

For direct-current generator panels or for the direct-current side 
of synchronous converters, two-wire system, there are usually required: 


Fig. 21. Wiring Diagram of D. C. Generator Panel 


1 Main switch 
1 Field switch 
1 Ammeter 
1 Voltmeter 

1 Field rheostat with controlling mechanism 
1 Circuit breaker 

1 4-point starting switch (for use when machine is to be started as a 
direct-current motor). 

Bus bars and various connections. 


These may be arranged in any suitable order, the circuit breaker 
being preferably located at the top so that any arcing which may 
occur will not injure other instruments. Fig. 21 gives a wiring dia¬ 
gram of such a panel. 

The main switch may be a single- or a double-throw, depending on 
whether one or two sets of bus bars are used. It may be a triple- 


417 



























52 


POWER STATIONS 


pole, as shown in Fig. 21, in which the middle bar serves as the equal¬ 
izing switch, or the equalizing switch may be mounted on a pedestal 
near the machine, in which case the generator switch would be 
double-pole. 

The field switch for large machines should be double-pole fitted 
with carbon breaks and arranged with a discharge resistance con¬ 
sisting of a resistance which is thrown across the terminals of the 



Fig. 22. Carbon Break Circuit Breaker 


field just before the main circuit is opened. One voltmeter located 
on a swinging bracket at the end of the panel, and arranged so that 
it can be thrown across any machine or across the bus bars by means 
of a dial switch, is sometimes used, but it is preferable to have a sej 
arate meter for each generator. 


418 








POWER STATIONS 


53 


Small rheostats are mounted on the back of the panel, but 
large ones are chain-operated and preferably located below the floor, 
the controlling hand wheel being mounted on the panel. 

The circuit breaker may be of the carbon break or the magnetic 
blow-out type. Figs. 22 and 23 show circuit breakers of these types. 
Lighting panels for low potentials are often fitted with fuses instead of 
circuit breakers, in which case they may be open fuses on the back 



Fig. 23. Magnetic Blow-Out Circuit Breaker 


of the panel or enclosed fuses on either the front or back of the 
panel. 

A panel for a direct-current generator or a synchronous converter 
for a 3-wire system should contain: 

2 Ammeters. 

2 Circuit breakers. Fuses used on small generators. 


419 








54 


POWER STATIONS 


Single-pole switches, double-throw if there are two sets of bus bars. For 
a three-wire generator or a synchronous converter two single-pole or one 
double-pole switch may be used, in which case the neutral wire is not 

' brought to the switchboard. 

Hand-wheels for the field rheostats. But one required if a three-wire gen¬ 
erator is used but the two are necessary if the three-wire system is ob¬ 
tained by the use of two generators or a balancer set. 

Field switches. But one is required for a three-wire generator or synchronous 
converter. 

Four-point Starting switch. Required. only when the 1 machine is to be 
started as a direct-current motor at times. 


2 Potential receptacles, four-point, used in connection with a voltmeter, 
usually mounted on a swinging bracket. Only one is required for the 
three-wire generator or the synchronous converter. 


An alternating-current generator or a synchronous motor panel 
for a three-phase, three-wire system will require: 


3 Ammeters. Only one required for a single-phase panel or for a synchronous 
motor. 

1 Three-phase indicating wattmeter. 

1 Voltmeter. 

1 8-point potential receptacle used to connect the above voltmeter across 
any phase. Not necessary for the synchronous motor. 

1 Field ammeter. Convenient but not always necessary. 

1 Double-pole field switch with discharge clips. 

1 Hand-wheel for field rheostat. 

1 Synchronizing receptacle. 

1 Triple-pole oil switch, usually non-automatic for generators but automatic 
for motors. This may be single- or double-throw, depending upon the 
bus bar arrangements. 

1 Synchronizer. A single instrument may serve for several machines. 

2 Current transformers. 

2 Potential transformers. Only one necessary for motor. 

1 Power Factor indicator. Not always necessary. 

1 Governor control switch. Not always necessary. 

Where the switches are of the remote control type, the control 
switches or the operating handles are mounted on the panel. 

A three-phase induction-motor panel should contain: 

1 Ammeter. 

1 Automatic oil switch, preferably operated by means of an inverse time¬ 
limit relay. 

The starting compensator used with induction motors is usually mounted 
independently of the switchboard panel. 

The instruments used on a synchronous converter panel, alternat¬ 
ing-current control, are: 


420 



POWER STATIONS 


55 


1 Ammeter. 

1 Synchronizing receptacle. 

1 Oil-switch, automatic. 

1 Potential transformer. 

2 Current transformers. 

1 Switch for control of regulator where a regulator is used and operated by 
means of a small motor. 

A three-phase feeder panel requires: 

3 Ammeters. In some cases only one is necessary. 

1 Automatic oil switch. 

2 Current transformers. 

1 Potential Transformer. Not always needed. 

1 Voltmeter. Not always needed. 

1 Hand-wheel for control of regulator where a regulator is used. 



Direct-Current feeder panels contain: 

1 Ammeter. Two are required for a 3-wire feeder. 

1 Circuit breaker, single-pole. Two are required for a 3-wire feeder. 

1 or more main switches, single-pole or double-pole, and single- or double¬ 
throw, depending upon the number of bus bars. 

1 Recording wattmeter, not always used. 

1 Potential receptacle. 

Apparatus for controlling regulators when such are used. 

One voltmeter usually serves for several feeder panels, such a 
meter being mounted above the panels or on a swinging bracket 
at the end. Switches should preferably be of the quick-break type. 
Figs. 24 and 25 show some standard switchboard panels as manu¬ 
factured by the General Electric Company. 





























56 


POWER STATIONS 


Exciter panels are nothing more than generator panels on a 
small scale. The necessary instruments for a panel controlling one 
exciter are: 

1 Ammeter. 

1 Field rheostat. 

1 Voltmeter. 

1 3-pole switch with fuses. 

1 4-point potential receptacle. 

1 Equalizing rheostat. This is necessary only where a Tirrill regulator is used 
and more than one exciter is operated on the same set of excitation buses. 



Fig. 25 . Standard Switchboard Panel 


Total Output Panels contain instruments recording the total 
power delivered by the plant to the switchboard. The paralleling 
of alternators is treated in “Management of Dynamo Electric Ma¬ 
chinery.” 

bor the higher voltages on alternating-current boards, the meas¬ 
uring instruments are no longer connected directly in the circuit, 
and the main switch is not mounted directly on the panel. Current 





















































































POWER STATIONS 


57 


and potential transformers, as called for in the lists given in connec¬ 
tion with the different panels, are used for connecting to the indi¬ 
cating voltmeters and the ammeters and the recording wattmeters, 
and potential transformers are used for the synchronizing device. 



Fig. 26. Three-Phase Oil Switch with Oil Container Removed 


These transformers are mounted at some distance from the panel, 
while the switches may be located near the panel and operated by a 
system of levers, or they may be located at a considerable distance 
and operated by electricity or by compressed air. 

Oil Switches. Oil switches are recommended for all high po- 
tential work for the following reasons: 

By tb°ir use it is possible to open circuits of higher potential and carry¬ 
ing greater currents than with any other type of switch. 


423 







58 


POWER STATIONS 


They may be made quite compact. 

They may readily be made automatic and thus serve as circuit breakers 
for the protection of machines and circuits when overloaded. 

There are several types of oil switches on the market. A switch 
constructed for three-phase work, to be closed by hand and to be 



Fig. 27. Three-Phase Oil Switch with Oil Container in Place 


electrically tripped or opened by hand, is shown in Fig. 26. This 
shows the switch without the can containing the oil. Fig. 27 shows 
a similar switch hand-operated, with the can in place. Both of 
these switches are arranged to be mounted on the panel. Fig. 28 
shows how the same switches are mounted when placed at some dis¬ 
tance from the panel. For high voltages, they are placed in brick 


424 









POWER STATIONS 


59 




425 












































































































































































60 


POWER STATIONS 


cells and often three separate single-pole switches are used, each 
placed in a separate cell so that injury to the contacts in one leg will in 
no way affect the other parts of the switch. A form of oil switch 
used for the higher potentials and currents met with in practice, 
is shown in Fig. 29. This particular switch is operated by 
means of an electric motor, though it may as readily be arranged to 
operate by means of a solenoid or by compressed air. General 




"fix 'fi 

SW/TCH CLOSED , SW/TCH OPEN \ 

' i (Motor j/;7/ running) } 

* 

SW/TCH OPEN'' 

(Motor .stopped} 

SW/TCH CLOSED SW/TCH CLOSED 

l /Motor still running) /Motor stopped} 


) 


Fig. 29. Form of Oil Switch for High Potentials 


practice is to place all high-tension bus bars and circuits in separate 
compartments formed by brick or cement, and duplicate bus bars 
are quite common. 

Oil switches are made automatic by means of tripping mag¬ 
nets, which are connected in the secondary circuits of current trans¬ 
formers, or they may be operated by means of relays fed from, the 
secondaries of current transformers in the main leads. Such relays 
are made very compact and can be mounted on the front or back 
of the switchboard panels. The wiring of such tripping devices is 
shown in Fig. 30. 


426 









































































POWER STATIONS 


61 


SOURCE 


LOAD 



SOURCE 


LOAD 


AU70MAT/C 
0/L SW/TCH 


TRIP COIL- 


With remote control of switches, the switchboard becomes in 
many instances more properly a switch house, a separate build¬ 
ing being devoted to the bus bars, 
switches and connections. In 
other cases a framework of angle 
bars or gas pipe is made for the 
support of the switches, bus bars, 
current and potential transform¬ 
ers, etc. The supports for the 
controlling switches are some¬ 
times mounted in a nearly hori¬ 
zontal position, forming the bench 
type of control board. 

Additional types of panels 
which may be mentioned are 
transformer panels, usually con¬ 
taining switching apparatus only, 
and arc-board panels. The latter 
are arranged to operate with plug 
switches. A single panel used in 
the operation of series transform¬ 
ers on arc-lighting circuits is 
shown in Fig. 31. 

Safety Devices. In addition 
to the ordinary overload tripping 
devices which have already been 
considered, there are various 
safety devices necessary in con¬ 
nection with the operation of cen¬ 
tral stations. One of the most 
important of these is the light¬ 
ning arrester. For direct-current 
work, the lightning arrester often 
takes the form of a single gap con¬ 
nected in series with a high resist- 
ance and fitted with some device for destroying the arc formed by 
discharge to the ground. One of these is connected between either 
side of the circuit and the ground, as shown diagrammatic-ally in 



SOURCE 


DOUBLE POLE RELAY 
CIRCUIT HORHALLY CLOSED 


LOAD 



Fig. 30. Wiring Diagram for Tripping 

Devices 


427 






























































62 


POWER STATIONS 



Fig. 32. A “kicking” coil is connected in circuit between the ar¬ 
resters and the machine to be protected, to aid in forcing the lightning 
discharge across the gap. In railway feeder panels such kicking 
coils are mounted on the backs of the panels. 


Fig. 31. Single Panel for Series Transformers in Arc-Lighting Circuits 


For alternating-current work, several gaps may be arranged in 
series, these gaps being formed between cylinders of “non-arcing” 
metal. High resistances and reactance coils are used with these, 
as in direct-current arresters. Fig. 33 shows connections for a 10,000- 
volt lightning arrester. The resistance used in connection with 
lightning arresters are of special design and non-inductive, In recent 


428 





















POWER STATIONS 


63 


types these resistances are connected in shunt to the gaps as shown in 
Fig. 34. Lightning arresters should always be provided with 
knife blade switches so that they can be disconnected from the cir¬ 
cuit for inspection and repairs. A typical installation of lightning 
arresters is shown in Fig. 35. 


Connections f or. Series Arc Lighting Circuits, up to 6000 Vo its . 


GERERA T0R5 




■Connections for Rai/wat/ Circuits up to 850 Vo its. {One side ^Grounded) 
REACTANCE CO/L 


GENERATOR, 


~L 


Reaction Coil is 
Composed of 85 ft. 
of Conductor Wound 
in a Cad of Two or 
Afore Turns as Con 
venient. 



Fig. 32. Lightning-Arrester Diagrams of D. C. Work 


In place of a series of gaps a single gap with terminals made in 
the form of horns is employed in some cases for lightning protection. 
Such an arrester is known as a horn gap, or horn arrester. The gap 
is connected between the line and the ground and when the po¬ 
tential strain becomes great enough the gap is broken down. The 
arc formed by the machine current after the gap is broken down 


429 












































/ 


POWER STATIONS 


0 * 



Fig. 33. Connections for 10,000-Volt Lightning Arrester 



430 



















































































































































POWER STATIONS 


65 



431 


Fig. 35. Typical Installation of Lightning Arresters 






















































POWER STATIONS 


00 

rises and lengthens until it can no longer be maintained by the gen¬ 
erator or generators in service. The horn arrester as applied to series 
lighting circuits is shown in Fig. 30. A series resistance, shown in 
the lower part of the figure, is used with this particular arrester. 

The most recent develop¬ 
ment in the way of light¬ 
ning protection is the intro¬ 
duction of the aluminum 
cell arrester. The elemen¬ 
tary cell consists of two 
aluminum plates, on which 
a film of aluminum hydrox¬ 
ide is formed, and which 
are immersed in a suitable 
electrolyte. The peculiar 
property of such a cell 
which makes it useful as 
a lightning arrester is that 
it has a high resistance up to a certain potential impressed upon 
it but when a critical value of voltage is reached, the resistance be¬ 
comes very low. The critical voltage for a single unit for alternating 
current is between 335 and 360 volts, and such a cell may be con¬ 
nected to a 300-volt circuit with only a very small current flow. 
For higher voltages, a number of cells are connected in series and 
a horn gap is inserted between the arrester and the line wire. The 
gap prevents any flow of current unless the arrester is brought into 
action by the discharge of excess line potential, in which case the 
aluminum cells offer a path of low resistance for the discharge of 
potential so long as the voltage is in excess of the critical voltage, 
but the machine or line potential, which is below the critical voltage 
of the arrester, cannot force enough current through the arrester 
circuit to maintain the arc at the gap. There is some dissolution 
of the film of hydroxide if the cell is left standing and not connected 
to the circuit, but it is readily formed again when the circuit is made. 
Arresters using a gap should have the gap closed for a short in¬ 
terval daily in order to insure a proper film on the aluminum plates. 
Views of the aluminum arrester are shown in Figs. 37 and 38. 

Reverse-current relays are installed when machines or lines 


r~ r 1 



Fig. 36. “Horn” Lightning Arrester 


432 







POWER STATIONS 


G7 


are operated in parallel. If two or more alternators are running and 
connected to the same set of bus bars, and one of these should fail 
to generate voltage by the opening of the field circuit, or some other 
cause, the other machine would feed into this generator and might 
cause considerable damage before the current flowing would be 
sufficient to operate the circuit breaker by means of the overload trip 
coils. To avoid this, reverse-current relays are used. They are so 



Fig. 37. Installation of Aluminum Lightning Arrester for 35,000 Volts 


arranged as to operate at, say f the normal current of the machine or 
line, but to operate only when the power is being delivered in the 
wrong direction. 

Speed-limit devices are used on both engines and rotary con¬ 
verters to prevent racing in the one case and running away in the 
second. Such devices act on the steam supply of engines and on 
the direct-current circuit breakers of rotary converters, respectively. 

Complete wiring diagrams for standard switchboards are shown 
in Figs. 39 and 40. 


433 


































68 


POWER STATIONS 


SUBSTATIONS 

Substations are for the purpose of transforming the high poten-' 
tials down to such potentials as can be used on motors or lamps, 
and in many cases to convert alternating current into direct current. 

Step-down transformers do not differ in 
any respect from step-up transformers.' 
Either motor-generator sets or rotary 
converters may be used to change from 
alternating to direct current. The for¬ 
mer consist of synchronous or induction 
motors, direct connected to direct-current 
generators, mounted on the same bed¬ 
plate. The generator may be shunt or 
compound wound, as desired. Rotary 
or synchronous converters are direct* 
current generators, though specially de¬ 
signed ; and they are fitted with collector 
rings attached to the winding at definite 
points. The alternating current is fed 
into these rings and the machine runs 
as a synchronous motor, while direct 
current is delivered at the commutator end. There is a fixed re¬ 
lation between the voltage applied to the alternating-current side 
and the direct-current voltage, which depends on the shape of the 
wave form, losses in the armature, pole pitch of the machine, method 
of connection, etc. The generally accepted values are given in 
Table XIII. 

The increase of capacity of six-phase machines over other 
machines of the same size is given in Table XIV. 

This increase is due to the fact that, with a greater number of 
phases, less of the winding is traversed by the current which passes ) 
through the converter. The saving by increasing the number of 
phases beyond six is but slight and the system becomes too complex. 
Rotary converters may be over-compounded by the addition of 
series fields, provided the reactance in the alternating circuits be 
of a proper value. It is customary to insert reactance coils in the 
leads from the low-tension side of the step-down transformers to the 
collector rings to bring the total reactance to a value which will insure 


TO HORN CAP 


METAL COVER 


WELDED 
STEEL TANK. 


E/EER 
/NJNLAT/OH 
TUBE —- 


ELECTROLYTE 

■CONED LN 
CROSS - 
SECT/ON 
ALNM/NUM 
CONES 
COMPLETE 

CENTER/NO 

CONTACT 

SPR/N6 



Fig. 38. Cross-Section of 
Aluminum Arrester 


434 

















435 



































































































































































436 


Fig. 40. Wiring Diagram for Standard Switchboard 








































































































































































































































































































































POWER STATIONS 71 


TABLE XIII 
Full Load Ratios 


Current 

Potential 

Per Cent 

Continuous 


100 

Two-phase i 

' 550 volts 

72.5 

and Six-phase - 

} 250 volts 

73 

(diametrical) ' 

-125 volts 

73.5 

Three-phase | 

' 550 volts 

62 

and Six-phase • 

\ 250 volts 

62 

(Y or delta) 

( 125 volts 

63 


the desired compounding. Again, the voltage may be controlled 
by means of induction regulators placed in the alternating-current 
leads. 

Two other methods of potential regulation for synchronous 
converters are in use. In the first of these methods a series gener¬ 
ator is used, this generator consisting of a polyphase armature at¬ 
tached to the rotary converter shaft and revolving in a separate 
field. The phases of this armature are connected between the col¬ 
lector rings of the machine and the taps to the converter armature, 
and the voltage impressed upon the converter taps amounts to the 
line voltage plus or minus the potential developed in the regulating 
armature. By means of a suitable field rheostat for the regulating 
field, any ordinary range of direct current at the brushes of the con¬ 
verter can be obtained with a constant voltage of alternating-current 
supply. Fig. 41 shows a converter equipped with this regulating 

device. 

In the regulating-pole converter each pole of the machine is 
made up of two parts, the main pole and the regulating pole. By 

TABLE XIV 
Capacity Ratios 


Continuous-current generator 

100 

Single-phase converter 

85 

Two-phase converter 

164 

Three-phase converter 

134 

Six-phase converter 

196 


437 















72 


POWER STATIONS 


varying the excitation of the regulating pole the ratio of conversion 
between the alternating-current voltage and the direct-current 
voltage can be changed through a considerable range—a sufficient 
range to cover the requirements ordinarily required in practice. 
Fig. 42 shows a view of a regulating pole converter. Motor-gen¬ 
erators are more costly and occupy more space than rotary con¬ 
verters but the regulation of the voltage is much better and they 
are to be preferred for lighting purposes. 



Fig. 41. Rotary Converter Equipped with Regulating Generator 

other buildings. While the detail of design and construction of the 
buildings for power plants belongs primarily to the architect, it is 
the duty of the electrical engineer to arrange the machinery to the 
best advantage, and he should always be consulted in regard to the 
general plans, at least, as this may save much time and expense in 
the way of necessary modifications. The general arrangement of 
the machinery will be taken up later, but a few points in connection 


BUILDINGS 

The power station usually has a building devoted entirely to 
this work, while the substations, if small, are often made a part of 


438 






POWER STATIONS 


73 


with the construction of the buildings and foundations will be con¬ 
sidered here. 

Space must be provided for the boilers—this may be a sepa¬ 
rate building—engine and. dynamo room, general and private offices, 
store rooms and repair shops. Very careful consideration should 
be given to each of these departments. The boiler room should be 
parallel with the engine room, so as to reduce the necessary amount 
of steam piping to a minimum, and if both rooms are in the same 
building a brick wall should separate the two, no openings which 
would allow dirt to come from the boiler room to the engine room 
being allowed. The height of both boiler and engine rooms should 



Fig. 42. Regulating-Pole Rotary Converter 


be such as to allow ample headway for lifting machinery and space 
for placing and repairing boilers, while provision should be made for 
extending these rooms in at least one direction. Roth engine and 
boiler rooms should be fitted with proper traveling cranes to fa¬ 
cilitate the handling of the units. In some cases the engines and 
dvnamos occupy separate rooms, but this is not general prac¬ 
tice. Ample light is necessary, especially in the engine rooms. The 
size of the offices, store rooms, etc., will depend entirely on local 
conditions. 


439 






74 


POWER STATIONS 


TABLE XV 



Thickness of Walls for Power Plants 


Width of 
Building 

CLEAR 

BETWEEN 

WALLS 

Height 

of 

Wall 

First Section 

Second Section 

Third Section 

Height 

Thickness 

Height 

Thickness 

Height 

Thickness 

25 feet 

40 feet 

40 feet 

12 inches 





25 feet 

40-60 feet 

40 feet 

16 inches 

To top 

12 inches 



25 feet 

60-75 feet 

25 feet ! 

20 inches 

To top 

16 inches 



25 feet 

75-85 feet 

20 feet 

24 inches) 

20-60 ft. 

20 inches 

To top 

16 inches 

25 feet 

85-100 ft. 

25 feet J 

28 inches 

25-50 ft. 

24 inches 

i 

50-75 feet 

20 inches 


Note. With clear space exceeding 25 feet the walls should be made 4 
inches thicker for each 10 feet or fraction thereof in excess of 25 feet. For 
buildings greater than 100 feet in height, each additional 25 feet or fraction 
thereof next above the curb shall be increased 4 inches in thickness. 

Foundations. The foundations for both the walls and the ma¬ 
chinery must be of the very best. It is well to excavate the entire 
space under the engine room to a depth of eight to ten feet so as to 
iorm a basement, while in most cases the excavations must be made 
to a greater depth for the walls. Foundation trenches are sometimes 
filled with concrete to a depth sufficient to form a good underfoot- 
ing. I he area of the foundation footing should be great enough 
to keep the pressure within a safe limit for the quality of the soil. 
The walls themselves may be of wood, brick, stone, or concrete. 
Wood is used for very small stations only, while brick may be used 
alone or in conjunction with steel framing, the latter construction 
being used to a considerable extent. If brick alone is used, the walls 
should never be less than twelve inches thick, and eighteen to twenty 
inches is better for large buildings. They must be amply reinforced 
with pilasters. Stone is used only for the most expensive stations. 

Table XV, which is taken from the New York Building Laws, 
may serve as a guide to the thickness of walls for power plants. 
Hie interior of the walls is formed of glazed brick, when the expense 
oi such construction is warranted. In fireproof construction, which 
is always desirable for power stations, the roofs are supported by 
steel trusses and take a great variety of forms. Fig. 43 shows what 
has been recommended as standard construction for lighting stations, 
showing both brick and wood construction. The floors of the engine 


440 























POWER STATIONS 


75 


room should be jmade of some material which will not form grit or 
dust. Hard tile, unglazed, set in cement or wood floors, is desirable. 
Storage battery rooms should be separate from all others and should 
have their interior lined with some material which will not be affected 
by the acid fumes. The best 'of ventilation is desirable for all parts 
of the station, but is of particular importance in the dynamo room 
if the machines are being heavily loaded. Substation construction 
does not differ from that of central stations when a separate build¬ 
ing is erected. They should be fireproof if possible. 

The foundations for machinery should be entirely separate 
from those of the building. Not only must the foundations be 



Fig. 43. Standard Construction for Lighting Station. Brick and Wood Construction 


stable, but in some locations it is particularly desirable that no 
vibrations be transmitted to adjoining rooms and buildings. A 
loose or sandy soil does not transmit such vibrations readily, but 
firm earth or rock transmits them almost perfectly. Sand, wool, 
hair, felt, mineral wool, and asphaltum concrete are some of the 
materials used to prevent this. The excavation for the foundation is 
made from 2 to 3 feet deeper and 2 to 3 feet wider on all sides than 
the foundation, and the sand, or whatever material is used, occupies 
this extra space, 


441 


































76 


POWER STATIONS 





CENTER 'OF SHAFTS 




/Vote • 

For bricA foundation a /Zin foot¬ 
ing of concrete stiou/d be /aid. 
Depth of foundation must be govern¬ 
ed by the character of the sod. 
Batter /to 6 

Foundation timbers and f/oonng 
shou/d be independent of station 
f/oor 




Fig. 45. Foundation for 150-Kw. Generator 


442 


/ 









































































































































































































































































POWER STATIONS 


77 


Brick, stone, or concrete is used for building up the greater 
part of machinery foundations, the machines being held in place 
by means of bolts fastened in masonry. A template, giving the 



For br/cA foundation a rZ inch 
footing of concrete should be 
te'd. Depth of foundation must 
be governed by the charact¬ 
er of the sod Batter t to 6 



Ik BOLTS 


tz BOLTSi 


rfrjp 


69 £ 






Fig. 46. Foundation for Rotary Converter 


location of all bolts to be used in holding the machine in place, 
should be furnished, and the bolts may be run inside of iron pipes 
with an internal diameter a little greater than the diameter of the 






EHGtHES 

SW/TCH BOARD 


D VS A MOD 


BO/LEF HOUSE 


EHG/HE DOOM 


Fig. 47. Diagram of Simple Arrange¬ 
ment of Belted Machines 



Fig. 48. Diagram of Arrangement of 
Machines Using Jack Shaft 


bolt. This allows some play to the bolt and is convenient for the 
final alignment of the machine. Fig. 44 gives an idea of this con¬ 
struction. The brickwork should consist of hard-burned brick of 
the best quality, and should be laid in cement mortar. It is well 
to fit brick or concrete foundations with a stone cap, forming a 
level surface on which to set the machinery, though this is not neces- 


443 
































































78 


POWER STATIONS, 



sary. Generators are sometimes mounted on wood bases to furnish i 
insulation for the frame. Fig. 45 shows the foundation for a 150- I 
kw. generator, while Fig. 46 shows the foundation for a rotary : 
converter. 


Station Arrangement. A few points have already been noted 


in regard to station arrangement, but the importance of the sub¬ 


ject demands a little further consider¬ 


ation. Station arrangement depends 


DYNAMO r 



chiefly upon two facts—the location and 
the machinery to be installed. Un¬ 
doubtedly the best arrangement is with 
all of the machinery on one floor with, 
perhaps, the operating switchboard , 
mounted on a gallery so that the at¬ 
tendants may have a clear view of all 
the machines. Fig. 47 shows the sim¬ 
plest arrangement of a plant using 


belted machines. Fig. 48 shows an arrangement of units where a 
jack shaft is used. Direct-current machines should be placed so 
that the brushes and commutators are easily accessible and the 


switchboard should be placed so 
as not to be liable to accidents, 
such as the breaking of a belt or 
a flywheel. 

When the cost of real estate 
prohibits the placing of all of the 
machinery on one floor, the en¬ 
gines may be placed on the first 
floor and belted to generators on 
the second floor, Fig. 49. It is 
always desirable to have the en¬ 
gines o:i the main floor, as they 




cause considerable vibration when 
not mounted on the best of 


EHG/ME ROOM 


QO/LER HOUSE 


Fig. 50. Diagram of Station Using Direct- 
Connected Units 


foundations. The boilers, while 


heavy, do not cause such vibration and they may be placed on the 
second or third floor. Belts should not be run vertically, as they 
must be stretched too tightly to prevent slipping. 


444 



























POWER STATIONS 


79 


Fig. 50 shows a large station using direct-connected units, while 
Figs. 51 and 52 show- the arrangement of the turbine plant of the 
Boston Edison Electric Illuminating Company. This station will 
contain twelve large turbine units when completed. Note the arrange¬ 
ment of boilers when several units are required for a single prime mover. 

The use of the steam turbine has led to the introduction of a 
type of station known as a double-deck -power plant and used in some 
instances where it is desirable to save space. In this type of sta¬ 
tion the boilers are placed on the ground floor and the turbines, 
which are of the horizontal type, are placed on a second floor directly 
above the boilers. Since there is but little vibration to the turbines 
and only light foundations are necessary, this construction may be 
readily carried out. Fig. 53 shows the general arrangement of 
such a plant. The use of a separate room or building for the cables, 
switches, and operating boards is becoming quite common for high- 
tension generating plants. The remarkable saving in floor space 
brought about by the turbine is readily seen from Fig. 54. The total 
floor space occupied by the 5,000 kw. units of the Boston station 
is 2.64 square feet per kw. This includes boilers—of which there 
are eight, each 512 h. p. for each unit—turbines, generators, switches, 
and all auxiliary apparatus. For the 10,000 and 15,000 kw. turbine 
sets now coming into use, this figure is still further reduced. 

When transformers are used for raising the voltage, they may 
be placed in a separate building, as is the case at Niagara Falls, or 
the transformers may be located in some part of the dynamo room, 
preferably in a line parallel to the generators. 

Fig. 55 shows the arrangement of units in a hydraulic plant. 
Fig. 56 is a good example of the practice in substation arrange¬ 
ment. The switchboard is at one end of the room, while the 
rotary converters and transformers are along either side. 

Large cable vaults are installed at the stations operating on 
underground systems, the separate ducts being spread out, and sheet- 
iron partitions erected to prevent damage being done to cables which 
were not originally defective, by a short circuit in any one feeder. 

Station Records. In order to accurately determine the cost of 
generating power and to check up on uneconomical or improper 
methods of- operation and lead to their improvement, accurately- 
kept station records are of the utmost importance. Such records 


445 


80 


POWER STATIONS 



446 


Fig. 51. Part Section of Turbine Plant. Boston Edison Luminating Company 
























































































































































































































POWER STATIONS 


Si 


n i Ol 


i"- -.i 

n iiC&C i 


M W'/SJ/fT' 

• ft yn 


\ nr 
: : : | 



447 


Plan of Turbines of Fig. 51 



























































































82 


POWER STATIONS 




« 

should consist of switchboard records, engine-room records, boiler- 
room records, and distributing-system records. Such records ac 
curately kept and properly plotted‘in the form of curves, serve ad¬ 
mirably for the comparison of station operations from day to day 
and for the same periods for different years. It pays to keep these 
records even when additional clerical force must be employed. 



In some states stations furnishing light or power to the public 
are required to make annual reports and the system of records, ac¬ 
counting, and form of report are all prescribed by the state. 

Switchboard records consist, in alternating stations, of daily 
readings of feeder, recording wattmeters, and total recording watt¬ 
meter, together with voltmeter and ammeter readings at intervals 


448 







































































































POWER STATIONS 


83 


of about 15 minutes, in some cases, to check upon the average 
power factor and determine the general form of the load curve. 
For direct-current lighting systems, volt and ampere readings serve 
to give the true output of the stations, and curves are readily plotted 
from these readings. The voltage should be recorded for the bus 
bars as well as for the centers of distribution. 




Fig. 54. Space Occupied by Turbo-Alternator Compared with that of Generator and 
Reciprocating Engine of Same Capacity 


Indicator diagrams should be taken from the engines at fre¬ 
quent intervals for the purpose of determining the operation of 
the valves. Engine-room records include labor; use of waste, oil, 
and supplies; as well as all repairs made on engines* dynamos and 
auxiliaries. 

Boiler-room records include labor and repairs, amount of coal 
used, which amount may be kept in detail if desirable, amount 




449 






























































































































































84 


POWER STATIONS 



of water used, together with steam-gauge record and periodical 
analysis of fine gases as a check on the methods of firing. 


Records for the distributing system include labor and ma¬ 
terial used for the lines and substations. For multiple-wire systems, 
frequent readings of the current in the different feeders will serve as a 
check on the balance of the load. 


450 
















POWER STATIONS 


85 



The cost of generating power varies greatly with the rate at 
which it is produced as well as upon local conditions. Station- 
operating expenses include cost of fuel, water, waste, oil, etc., cost 
of repairs, labor, and superintendence. Fixed charges include 
insurance, taxes, interest on investment, depreciation, and general 
office expenses. lotal expenses divided by total kilowatt-hours gives 


Fig. 56. A Good Arrangement of Apparatus for Substation 

the cost of generation of a kilowatt-hour. The cost of distributing a 
kilowatt hour may be determined in a similar manner. The rate 
of depreciation of apparatus differs greatly with different machines, 
but the following figures may be taken as average values, these fig¬ 
ures representing percentage of first cost to be charged up each year: 

Fireproof buildings from 2 to 3 per cent. 

Frame buildings from 5 to 8 per cent. 

Dynamos from 2 to 4 per cent. 

Prime movers from 2\ to 5 per cent. 

Boilers from 4 to 5 per cent. 

Overhead lines, best constructed, 5 to 10 per cent. 

More poorly constructed lines 20 to 30 per cent. 

Badly constructed lines 40 to 60 per cent. 

Underground conduits 2 per cent. 

Lead covered cables 2 per cent. 


451 
















80 


POWER STATIONS 


Methods of Charging for Power. There are four methods 

used for charging consumers for electrical energy, namely, the flat- 
rate, or contract, system, the meter system, the two-rate meter system, * 
and a system hy which each customer pays a fixed amount depending 
on the maximum demand and in addition pays at a reasonable rate for 
the power actually used. 

In the flat-rate system, each customer pays a certain amount a 
year for service, this amount being based on the estimated amount 
of power to be used. These rates vary, depending on the hours of 
the day during which the power is to be used, being greatest if the 
energy is to be used during peak hours. It is an unsatisfactory method 
for lighting service, as many customers are liable to take advantage 
of the company, burning more lights than contracted for and at 
different hours, while the honest customer must pay a higher rate 
than is reasonable in order to make the station operation profitable. 
This method serves much better when the power is used for driving 
motors, and is used largely for this class of service. 

The simple meter method of charging serves the purpose bet¬ 
ter for lighting, but the rate here is the same no matter what hour 
of the day the current is used. Obviously, since machinery is in¬ 
stalled to carry the peak of the load, any power used at this time 
tends to increase the capital outlay from the plant, and users should 
be required to pay more for the power at such times. The meter 
system is often employed with a sliding scale or rate, the rate charged 
per kw.-hour depending upon the amount of electrical energy used. 

The two-rate meter accomplishes this purpose to a certain 
extent. The meters are arranged so that they record at two rates, 
the higher rate being used during the hours of heavy load. 

There are several methods of carrying out the fourth scheme. 
In the Brighton System a fixed charge is made each month, de¬ 
pending on the maximum demand for power during the previous 
month, a regular schedule of such charges being made out, based • 
on the cost of the plant. An integrating wattmeter is used to re¬ 
cord the energy consumed, while a so-called “demand meter” records 
the maximum rate of demand. 


452 


Bibliography 


% 


T HE following list of books on (he various subjects of Engineering is not 
intended to be complete, but represents the best book literature in the 
field. Unfortunately, on account of lack of space, the many short 
pamphlets, addresses, and reprints from periodicals, containing a wealth of 
authoritative information, cannot be included. For these the reader is referred 
to the annuals and quarterlies of the various engineering organizations and to 
the libraries. 


ABRAHAM-BAY LE: Steam Economy in 
the Sugar Factory. 96 pp. John Wiley 
& Sons. 

ALLEN-BL RSLEY: Heat Engines; steam, 
gas,-steam turbines, and their aux¬ 
iliaries. A. C. McClurg & Company. 

ALLEN, H.: Modern Power Gas-Pro¬ 
ducer Practice and Application. 344 
pp. Van Nostrand Company. 

AUCHINCLOSS, W. S.: The Practical 
Application of the Slide Valve and 
Link Motion to Stationary, Portable, 
Locomotive, and Marine Engines. 15th 
edition, revised. 144 pp. Van Nost¬ 
rand Company. 

BACON, F. W.: A Treatise on the Rich¬ 
ards Steam Engine Indicator. 4th edi¬ 
tion. 180 pp. Van Nostrand Company. 

BALDWIN, WILLIAM J.: Baldwin on 
Heating. 16th edition, revised and 
enlarged. 404 pp. John Wiley & Sons. 

. Hot Water Heating and Fitting. 

The methods of construction and the 
principles involved. 4th edition, revis¬ 
ed and enlarged. 306 pp. McGraw-Hill 
Company. 

. Heating. Steam heating for 

buildings, revised. A. C. McClurg & 
Company. 

BALE, M. P.: Pumps and Pumping. 5th 
edition. 121 pp. Van Nostrand Com¬ 
pany. 

BALL, R. S.: Natural Sources of Power. 
364 pp. Van Nostrand Company. 

BARKER, A. H.: Graphic Methods of En¬ 
gine Design. 2nd edition. 217 pp. 
Van Nostrand Company. 

BARR, WILLIAM M.: Combustion of 
Coal and the Prevention of Smoke. 
A. C. McClurg & Company. 

BARRUS, G. H.: Boiler Tests. 252 pp. 
Van Nostrand Company. 

. Engine Tests. 338 pp. Van 

Nostrand Company. 


BARTLETT, F. W.: Mechanical Drawing. 
3rd edition, revised. 164 pp. John 
Wiley & Sons. 

BAXTER, WILLIAM, Jr.: Hydraulic Ele¬ 
vators. 300 pp. McGraw-Hill Company. 

BEGTRUP, JULIUS: The Slide-Valve 
and its Functions. With special refer¬ 
ence to modern practice in the United 
States. A. C. McClurg & Company. 

BERRY, CHARLES W.: The Tempera¬ 
ture-Entropy Diagram. 3rd edition, re¬ 
vised and enlarged. 393 pp. John 
Wiley & Sons. 

BF.RTIN, L. E.: Marine Boilers. Their 
Construction and Working. 2nd edition, 
revised and enlarged. 694 pp. Van 
Nostrand Company. 

BOOTH, W. II.: Superheaters, Superheat¬ 
ing, and Their Control. 170 pp. Van 
Nostrand Company. 

. Water Softening and Treatment. 

308 pp. Van Nostrand Company. 

BOWKER, WILLIAM R.: Dynamos, Mo¬ 
tors, and Switchboard Circuits. Deals 
with direct, alternating, and polyphase 
currents. Van Nostrand Company. 

BOYCOTT, G. W. M.: Compressed-Air 
Work and Diving. A handbook for 
engineers, comprising deep water div¬ 
ing and the use of compressed air for 
sinking caissons and cylinders and for 
driving subaqueous tunnels. A. C. 
McClurg & Company. 

BRACKETT, C. F., AND OTHERS: Elec¬ 
tricity in Daily Life. A popular ac¬ 
count of the application of electricity 
to everyday use. A. C. McClurg & 
Company. 

BRAGG, E. M.: Marine Engine Design. 
175 pp. Van Nostrand Company. 

BRANCH, JOSEPH G.: Conversations on 
Electricity. An elementary book. 282 
pp. Rand McNally & Company. 


453 






9 


BIBLIOGRAPHY 


BROMLEY-COBLEIGH: Mathematics for 
the Practical Engineer. 220 pp. McGraw- 
Hill Company. 

BURNS-BRANCH: Practical Mathematics 
for the Engineer and Electrician. Cov¬ 
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derstand alternating currents. Riley & 
Sons. 

BURNS, ELMER E.: The Electric Motor 
its Practical Operation. Treats of the 
principles and operation of all kinds of 
motors. 191 pp. Numerous tables. Ri¬ 
ley & Sons. 

CARDULLO, FORREST E.: Practical 
Thermodynamics. A clear treatment of 
the natural laws and physical princi¬ 
ples which underlie the action of ther¬ 
modynamic apparatus. 414 pp. McGraw- 
Hill Company. 

CARPENTER-DIEDERICHS: Experimen¬ 
tal Engineering and Manual for Test¬ 
ing. 7th edition, rewritten and en¬ 
larged. 1132 pp. John Wiley & Sons. 

. Internal-Combustion Engines. 

Their theory, construction and opera¬ 
tion. A. C. McClurg & Company. 

CARPENTER, R. C.: Heating and Ven¬ 
tilating Buildings. A manual for heat¬ 
ing engineers and architects. A. C. 
McClurg & Company. 

. The Heating and Ventilation of 

Buildings. 5th edition, revised. 562 
pp. John Wiley & Sons. 

CHALKLEY, A. P.: Diesel Engines for 
Land and Marine Work. 237 pp. Van 
Nostrand Company. 

CHILD, CHARLES T.: The How and 
Why of Electricity. A book of infor¬ 
mation for non-technical readers. Van 
Nostrand Company. 

CHRISTIE, W. W.: Chimney Design and 
Theory. 2nd edition, revised and en¬ 
larged. 200 pp. Van Nostrand Com¬ 
pany. 

. Water, Its Purification and Use 

in the Industries. 230 pp. Van Nos¬ 
trand Company. 

CLARK, CARL H.: Marine Gas Engines. 
Their Construction and Management. 
117 pp. Van Nostrand Company. 

(LARK, D. K.: Fuel: Its Combustion 
and Economy. 4th edition. 366 pp. 
Van Nostrand Company. 

CLERK, DUGALD: The Gas and Oil En¬ 
gine. A. C. McClurg & Company. 

. The Gas, Petrol, and Oil Engine. 

Thermodynamics of the gas, petrol, and 
oil engine, together with historical 
sketch. New and revised edition. 

COLLINS, HUBERT E.: Boilers. Mc¬ 
Graw-Hill Company. 

. Erecting Work. McGraw-Hill 

Company. 


. Knocks and Kinks. McGraw- 

Hill Company. 

. Pipes and Piping. McGraw- 

Hill Company. 

. Pumps. McGraw-Hill Company. 

. Shaft Governors. McGraw-Hill 

Company. 

. Shafting, Pulleys, Belting and 

Rope Transmission. McGraw-Hill Com¬ 
pany. 

. Steam Turbines. McGraw-Hill 

Company. 

. Steam Turbines. A book of in¬ 
struction for the adjustment and opera¬ 
tion of the principal types of this class 
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Company. 

. Valve Setting; simple methods 

of setting the plain slide valve, Meyer 
cutoff, Corliss, and Poppet types. A. C. 
McClurg & Company. 

COOLIDGE, C. E.: A Manual of Drawing. 
92 pp. John Wiley & Sons. 

CREIGHTON, W. II.: Steam Engine and 
Other Heat Motors. 2nd edition, re- 
vised and enlarged. 598 pp. John 
Wiley & Sons. 

CROCKER-ARENDT: Electric Motors. 

Their action, control, and application. 
296 pp. McGraw-Hill Company. 

CROCKER-WHEELER: Management of 

Electrical Machinery. A. C. McClurg 
& Company. 

.. Practical Management of Dy¬ 
namos and Motors. 206 pp. Spoil & 
Chamberlain. 

CROCKER, FRANCIS B.: Electric Light¬ 
ing. In two volumes. Vol. I: The 
Generating Plant. Vol. II: Distribut¬ 
ing System and Lamps. McGraw-Hill 
Company. 

CROMWELL, J. HOWARD: A Treatise 
on Belts and Pulleys. 271 pp. John 
Wiley & Sons. 

.. A Treatise on Toothed Gearing. 

245 pp. John Wiley & Sons. 

CUSHING, II. C., JR.: Standard Wiring 
for Electric Light and Power. Van 
Nostrand Company. 

DAY, >C.: Indicator Diagrams and Engine 
and Boiler Testing. 4th edition. 220 
pp. Van Nostrand Company. 

DINGER, Id. C.: Handbook for the Care 
and Operation of Naval Machinery. 2nd 
edition. 312 pp. Van Nostrand Com¬ 
pany. 

DRAPER, CHARLES H.: Heat and the 
Principles of Thermodynamics. New 
and revised edition. 444 pp. Van Nos¬ 
trand Company. 

DUBBEL, H.: High Power Gas Engines. 
200 pp. Van Nostrand Company. 


454 






















BIBLIOGRAPHY 


3 


DURAND, W. F.: Practical Marine En¬ 
gineering. For marine engineers and 
students, with aids for applicants for 
marine engineers’ licenses. A. C. Mc- 
Clurg & Company. 

ELLENWOOD, F. O.: Steam Charts. John 
Wiley & Sons. 

ENNIS, WILLIAM D.: Applied Ther¬ 
modynamics for Engineers. 3rd edi¬ 
tion, revised and enlarged. 514 pp 
Van Nostrand Company. 

EWING, J. A.: The Steam Engine and 
Other Heat Engines. 3rd edition, re¬ 
vised and enlarged. A. C. McClurg & 
Company. 

FLATHER, J. J.: Rope Driving. 230 pp. 
John Wiley & Sons. 

FOSTER, HORATIO A.: Electrical En¬ 
gineer’s Pocketbook. Tables, data, and 
formulas relating to all branches of 
electrical application. 6th edition, com¬ 
pletely revised and enlarged. Pocket 
size. Flexible leather. 1636 pp. 1912. 
McGraw-Hill Company. 

FRANKLIN-ESTY: Elements of Electrical 
Engineering. Two vols. Van Nostrand 
Company. 

FRENCH, LESTER G.: Steam Turbines. 
A comprehensive treatment of the whole 
subject. 418 pp. McGraw-Hill Com¬ 
pany. 

FRENCH, THOMAS E.: Engineering 
Drawing. 289 pp. McGraw-Hill Com¬ 
pany. 

GARCKE-FELLS: Factory Accounts. A 

new enlarged edition of the standard 
English treatise on Factory Accounting. 
292 pp. McGraw-Hill Company. 

GEAR-WILLIAMS: Electric Central Sta¬ 
tion Distribution Systems. Their de¬ 
sign and construction. 352 pp. 1911. 
Van Nostrand Company. 

GEBHARDT, G. F.: Steam Power Plant 
Engineering. 4th edition, revised and 
enlarged. 989 pp. John Wiley & Sons. 

GILL, AUGUSTUS H.: Engine Room 
Chemistry. McGraw-Hill Company. 

. Gas and Fuel Analysis for En¬ 
gineers. 7th edition, revised and en¬ 
larged. 141 pp. John Wiley & Sons. 

GOING, CHARLES B.: Principles of In¬ 
dustrial Engineering. 174 pp. McGraw- 
Hill Company. 

GOODEVE, T. M.: Textbook on the Steam 
Engine. 15th edition. 416 pp. Van 
Nostrand Company. 

GOULD, E. S.: The Arithmetic of the 
Steam Engine. 80 pp. Van Nostrand 
Company. 

GOSS, W. F.: Locomotive Performance. 
439 pp. John Wiley & Sons. 

. Locomotive Sparks. 172 pp. John 

Wiley & Sons, 


GREENE, ARTHUR M.: Elements of 
Heating and Ventilation. 324 pp. John 
Wiley & Sons. 

. Elements of Refrigeration. John 

Wiley & Sons. 

. Pumping Machinery. 703 pp. 

John Wiley & Sons. 

GRIMSHAW, R.: Engine Runner’s Cate¬ 
chism. Tells how- to erect, adjust, and 
run the principal steam engines in use 
in the United States; describes the 
principal features of the different en¬ 
gines. A. C. McClurg & Company. 

. Steam Engine Catechism. Prac¬ 
tical answers to practical questions. 
A. C. McClurg & Company. 

GROVER. F.: Practical Treatise on Mod¬ 
ern Gas and Oil Engines. 5th edition. 
380 pp. Van Nostrand Company. 

GULDNER, HUGO: The Design and Con¬ 
struction of Internal-Combustion En¬ 
gines. 2nd edition, revised and en¬ 
larged. A. C. McClurg & Company. 

HAEDER, II.: A Handbook on the Steam 
Engine. 3rd edition, revised. 465 pp. 
Van Nostrand Company. 

IIAEDER-HUSKISSON: A Handbook on 
the Gas Engine. 330 pp. McGraw-Hill 
Company. 

HALL, II. R.: Governors and Governing 
Mechanism. 2nd edition, enlarged. 188 
pp. Van Nostrand Company. 

HALSEY, F. A.: Slide Valve Gears. 12th 
edition, revised and enlarged. 213 pp. 
Van Nostrand Company. 

HARRIS, ELMO G.: Compressed Air. 
Theory and computations. 123 pp. Mc¬ 
Graw-Hill Company. 

HARTMAN, FRANCIS M.: Heat and 
Thermodynamics. 346 pp. McGraw-Hill 
Company. 

HAUSBRAND, E.: Drying by Means, of 
Air and Steam. 77 pp. Van Nostrand 
Company. 

. Evaporating, Condensing, and 

Cooling Apparatus. 400 pp. Van Nost¬ 
rand Company. 

HAVEN-SWETT: The Design of Boilers 
and Pressure Vessels. John Wiley & 
Sons. 

HAWKINS, GEO. W.: Economy Factor 
in Steam Power Plants. Diagrams, 
graphs, and tables of the greatest value 
to the modern power plant. 133 pp. 
McGraw-Hill Company. 

HAWKINS, N.: Handbook of Calculations 
for Engineers. Relating to the steam 
engine, the steam boiler, pumps, shaft¬ 
ing, etc. A. C. McClurg & Company. . 

. Instructions for the Boiler Room. 

Useful to engineers, firemen, and me¬ 
chanics. A. C. McClurg & Company. 

. New Catechism of the Steam 

Engine. A- C. McClurg & Company. 


455 















4 


BIBLIOGRAPHY 


HAWKINS-WALLIS: The Dynamo, Its 
Theory, Design, and Maintenance. Di¬ 
rect and Alternating Currents. Two 
vols. A. C. McClurg & Company. 

HECK, ROBERT C. H.: The Steam En¬ 
gine and Other Steam Motors. Two 
vols. Van Nostrand Company. 

. The Stegm Engine and Turbine. 

625 pp. Van Nostrand Company. 

HEMENWAY, FRANK F.: Indicator 
Practice and Steam-Engine Economy. 
184 pp. John Wiley & Sons. 

HENRY-IIORA: Modern Electricity. A 
textbook for students and apprentices. 
355 pp. Laird & Lee. 

HIRSIIFELD-BARNARD: Elements of 

Heat-Power Engineering. 811 pp. John 
Wiley & Sons. 

HIRSHFELD, C. F.: Engineering Ther¬ 
modynamics. 2nd edition. 162 pp. Van 
Nostrand Company. 

HIRSHFELD-ULBRICHT: Gas Engines 
for the Farm. 239 pp. John Wiley & 
Sons. 

. Gas Power. 209 pp. John Wiley 

& Sons. 

. Steam Power. John Wiley & 

Sons. 

HISCOX, G. D.: Gas, Gasoline, and Oil 
Engines. Including producer-gas plants. 
A. C. McClurg & Company. 

HOBART-ELLIS: Armature Construction. 
348 pp. Macmillan Company. 

HOBART, HENRY M.: Design of Poly¬ 
phase Generators and Motors. 260 pp. 
McGraw-Hill Company. 

. Electricity. A textbook designed 

particularly for engineering students. 
226 pp. 43 tables. 1910. Van Nostrand 
Company. 

. Electric Motors. Continuous, 

polyphase, and single-phase motors. 
Their theory and construction. Revised 
and enlarged. 736 pp. Macmillan Com¬ 
pany. 

HOFFMAN, JAMES D.: Handbook for 
Heating and Ventilating Engineers. 
A practical discussion, with tables and 
charts, on design and installation. 402 
pp. McGraw-Hill Company. 

HOGLE, W. M.: Internal Combustion 
Engines. A reference book for design¬ 
ers, operators, engineers, and students. 
256 pp. McGraw-Hill Company. 

HOLMES, G. C. V.: Steam Engine. An 
elementary treatise supplementary to 
the study of physics. A. C. McClurg 
& Company. 

HOOPER-WELLS: Electric Handbook for 
Engineering Students. 170 pp. Ginn & 
Company. 


HOPKINS, N. M.: Model Engines and 
Small Boats. 84 pp. Van Nostrand 
Company. 

HORSTMAN-TOUSLEY: Modern Wiring 
Diagrams and Designs. 293 pp. F. J. . 
Drake & Company. 

. Practical Armature and Magnet 

Winding. 230 pp. 1909. A. C. McClurg 
& Company. 

1IOUSTON-KENNELLY: The Electric 

Motor. 377 pp. A. C. McClurg & Com¬ 
pany. 

HUBBARD, CHARLES L.: Heating and 
Ventilating Plants. 2nd edition. 300 
pp. McGraw-IJill Company. 

’.. Power, Heating, and Ventila¬ 

tion. A series of three distinct works 
on the design, construction and man¬ 
agement of power, heating, and ventilat¬ 
ing plants. McGraw-Hill Company. 

. Steam Power Plants. 2nd edi¬ 
tion. 300 pp. McGraw-Hill Company. 

HUTTON, F. R-.: Heat and Heat-Engines. 

A study of the principles which under¬ 
lie the mechanical engineering of a 
power plant. A. C. McClurg & Com- j 
pany. 

. The Gas Engine. A treatise on 

the internal-combustion engine using 
gas, gasoline, kerosene, or other hydro¬ 
carbons, as source of energy. A. C. Mc¬ 
Clurg & Company. 

. The Mechanical Engineering of 

Power Plants. A. C. McClurg & Com¬ 
pany. 

. The Gas Engine. 3rd edition, 

revised. 562 pp. John Wiley & Sons. 

. Mechanical Engineering of 

Steam Power plants. 3rd edition, re¬ 
written. John Wiley & Sons. 

IH TTON, W. S.: Practical Engineer’s 
Handbook. Comprising a treatise on 
modern engines and boilers, marine 
locomotive, and stationary. 7th edi¬ 
tion, revised and enlarged. 577 pp. 
Van Nostrand Company. 

. Steam Boiler Construction. 4th 

edition, revised and enlarged. 675 pp. 
Van Nostrand Company. 

IBBETSON, W. S.: Practical Electrical 
Engineering for Elementary Students 
167 pp. 1910. Van Nostrand Company. 

INNES, C. II.: Air Compressors and Blow¬ 
ing Engines. 300 pp. Van Nostrand 
Company. 

. Centrifugal Pumps, Turbines 

and Water Motors. 5th edition, 350 pp. 
Van Nostrand Company. 

. The Fan: Including the Theory 

and Practice of Centrifugal and Axial 
Fans. 258 pp. Van Nostrand Company. 

ENS, EDMUND M.: Pumping By Com¬ 
pressed Air. John Wiley & Sons. 


456 



















BIBLIOGRAPHY 


5 


JAMES-DOLE: Mechanism of the Steam 
Engine and Similar Machines. John 
Wiley & Sons. 

TONES, FORREST R.: The Gas Engine. 
447 pp. John Wiley & Sons. 

JUNGE, F. E.: Gas Power. The full story 
of gas power, its generation, transmis¬ 
sion, and application, with especial ref¬ 
erence to large engines. 548 pp. Mc¬ 
Graw-Hill Company. 

KELLEY, H. H.: Engineer’s Examiner. 
160 pp. McGraw-Hill Company. 

.Engine Room Instructor. A col¬ 
lection of the absolutely necessary 
tables required by the engineer. 80 pp. 
McGraw-Hill Company. 

KENNEDY, R.: Modern Engines and 
Power Generators. A practical work 
on prime movers and the transmission 
of power; steam, electric, water, and 
hot air. Six vols. Van Nostrand Com- 
pany. 

KENT, WILLIAM: Investigating an In¬ 
dustry. 126 pp. John Wiley & Sons. 

. The Mechanical Engineers’ 

Pocket Book. 8th edition, revised and 
enlarged. 1461 pp. John Wiley & Sons. 

..:. Steam-Boiler Economy. A trea¬ 

tise on the theory and practice of fuel 
economy in the operation of steam 
boilers. A. C. McClurg & Company. 

KEOWN, R. McA.: Mechanism. 170 pp. 
McGraw-Hill Company. 

KERR, E. W.: Power and Power Trans¬ 
mission. Deals with power transmis¬ 
sion and generation by the common 
means other than electrical. A. C. Mc¬ 
Clurg & Company. 

KERSHAW, J. B. C.: Fuel, Water, and 
Gas Analysis. 167 pp. Van Nostrand 
Company. 

KING, WILLIAM R.: Steam Engineering. 
450 pp. John Wiley & Sons. 

. The Elements of the Mechanics 

of Materials and of Power Transmis¬ 
sion. 266 pp. John Wiley & Sons. 

KIRSCHKE, A.: Gas and Oil Engines.. 
160 pp. Van Nostrand Company. 

KLEIN, J. F.: Design of a High Speed 
Steam Engine. 2nd edition, revised 
and enlarged. 257 pp. Van Nostrand 
Company. 

KNEASS, STRICKLAND L.: Practice 
and Theory of the Injector. 3rd edi¬ 
tion, revised and enlarged. 175 pp. 
John Wiley & Sons. 

KNOX, C. E.: Electric Light Wiring. 219 
pp. McGraw-Hill Company. 

ICOESTER, FRANK: Steam Electric Power 
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LALL1ER, ERNEST V.: An Elementary 
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Van Nostrand Company. 

LATTA, NISBET: American Producer 
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LEASK, A. R.: Refrigerating Machinery. 
4th edition. 296 pp. Van Nostrand 
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LEDOUX, M.: Ice-Making Machines. The 
theory of the action of the various 
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LEVIN, A. M.: The Modern Gas Engine 
and the Gas Producer. 485 pp. John 
Wiley & Sons. 

LEWES, V. B.: Liquid and Gaseous Fuels 
and the Part They Play in Modern 
Power Production. 348 pp. Van Nost¬ 
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LINEHAM, WILFRID J.: A Textbook 
of Mechanical Engineering. 2 parts. 
A. C. McClurg & Company. 

LODGE, WILLIAM: Rules of Manage¬ 
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LOEWENSTEIN, L. C„ and CRISSEY, 
C. P.: Centrifugal Pumps, Their De¬ 
sign and Construction. 432 pp. Van 
Nostrand Company. 

LOW, F. R.: Condensers. 79 pp. Mc¬ 
Graw-Hill Company. 

. The Steam Engine Indicator. 

Direction for the selection, care, and 
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. The Compound Engine. 52 pp. 

McGraw-Hill Company. 

LUCKE, CHARLES EDWARD: Engineer¬ 
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LUCKE, C. E.: Gas Engine Design. A. 
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MACINTIRE, H. J.: Mechanical Refrig¬ 
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MAC CORD, C. W.: Slide Valves. 168 
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. Velocity Diagrams. Their con¬ 
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MAHAN-THOMPSON: Industrial Draw¬ 
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MARKS-DAVIS: Tables and Diagrams of 
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& Company. 









BIBLIOGRAPHY 


MARKS, E. C. R.: Notes on the Con¬ 
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MARLOW, THOMAS G.: Drying Machin¬ 
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458 
















BIBLIOGRAPHY 


/ 


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459 











BIBLIOGRAPHY 


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SOTHERN, J. W.: Marine Steam Turbine. 
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SPANGLER, H. W.: Notes on Thermody¬ 
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SWOOPE, C. WALTON: LessonsJn Prac¬ 
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460 






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Their Design, Construction, and Oper¬ 
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2 parts. A. C. McClurg & Company. 

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TULLEY, HENRY C.: Handbook on En¬ 
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WALKER, SYDNEY F.: A Pocketbook of 
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WATERBURY, L. A.: Laboratory Manual 
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WEHRENFENNIG-PATTERSON: Analy¬ 
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461 
















REVIEW QUESTIONS 



REVIEW QUESTIONS 

ON THE SUBJECT OF 

HEATING AND VENTILATION 

PART I 


1. What advantage does indirect steam heating have over 
direct heating? What advantages over furnace heating? 

2. What are the causes of heat loss from a building? 

3. Why is hot water especially adapted to the warming of 
dwellings? 

4. What proportion of carbonic acid gas is found in outdoor 
air und^r ordinary conditions? 

5. A room in the N. E. corner of a building of fairly good con¬ 
struction is 18 feet square and 10 feet high; there are 5 single 
windows, each 3 by 10 feet in size. The walls are of brick 12 inches 
in thickness. With an inside temperature of 70 degrees, what will 
be the heat loss per hour in zero weather? 

6. State four important points to be noted in the care of a 
furnace. 

7. A grammar school building, constructed in the most thor¬ 
ough manner, has 4 rooms, one in each corner, each being 30 ft. by 
30 ft. and 14 ft. high, and seating 50 pupils. The walls are of 
wooden construction and the windows make up $ the total 
exposed surface. The basement and attic are warm. How many 
pounds of coal will be required per hour for both heating and ven¬ 
tilation in zero weather, if 8,000 B. T. U. are utilized from each 
pound of coal? 

8. What two distinct types of furnaces are used? What are 
the distinguishing features? 

9. What is meant by the efficiency of a furnace? What 
efficiencies are obtained in ordinary practice? 


463 






REVIEW QUESTIONS 

ON THE SUBJECT OF 

HEATING AND VENTILATION 

PART II 


1. How would you obtain the sizes of the cold-air and 
warm-air pipes connecting with indirect heaters in dwelling-house 
work? 

2. What is an aspirating coil, and what is its use? 

3. What efficiencies may be allowed for indirect heaters in 
schoolhouse work? How would you compute the size of an indirect 
heater for a room in a dwelling-house? 

4. How is the size of a direct-indirect radiator computed? 

5. A schoolroom on the third floor is to be supplied with 
2,400 cubic feet of air per minute. What should be the area of the 
warm-air supply flue? 

6. What is the chief objection to a mixing damper, and how 
may this be overcome? 

7. How many square feet of indirect radiation will be required 
to warm and ventilate a schoolroom when it is 10 degrees below 
zero, if the heat loss through walls and windows is 42,000 B. T. U. r 
and the air-supply 120,000 cubic feet per hour? 

8. What is the difference in construction between a steam 
radiator and one designed for hot water? Can the steam radiator 
be used for hot water? State reasons for answer. 

9. How may the piping in a hot-water system be arranged so 
that no air-valves will be required on the radiators? 

10. What efficiency is commonly obtained from a direct hot- 
water radiator? How is this computed? 

11. How should the pipes be graded in making the connec¬ 
tions with indirect hot-water heaters? Where should the air-valve 
be placed? 

12. Describe briefly one form of grease extractor. 


464 






REVIEW QUESTIONS 


ON THE SUBJECT OF 

MANAGEMENT OF DYNAMO-ELECTRIC 
MACHINERY 

PART I 


1. What items are to be considered in selecting a machine? 

2. What means are applied for connecting the engine, or 
other prime movers, with the generator? 

3. State the formula for determining the approximate 
width of a single belt required to transmit a given horsepower. 

4. What are the advantages of rope driving? 

5. What is the usual speed of shafting employed in textile 

mills? 

6. Give diagram for connecting shunt type of direct-current 
generator. 

7. Explain how to run two compound-wound generators in 
parallel. 

8. What is the chief difference in appearance of a synchro¬ 
nous converter as compared with a direct-current generator? 

9. Considering a six-phase rotary converter, the alternating 
current across phases 1 and 2 is 1000 volts. What is the direct 
current? 

10. Give wiring connection for two direct-current generators 
on a three-wire system. 

11. How is the speed control of a shunt motor obtained? 

12. What is a differentially-wound motor? 

13. Considering a three-phase generator Y connected, what 
is the value of the line current in comparison with the current per 
phase? 

14. How is the direction of rotation of induction motors 
reversed? 

15. Give the characteristics of repulsion induction motors. 


465 



REVIEW QUESTIONS 




ON the SUBJECT OF 

MANAGEMENT OF DYNAMO-ELECTRIC 
MACHINERY 

PART .II 


1. How can the friction of the bearings and brushes be 
roughly tested? 

2. Which is the most accurate way to determine the tem¬ 
perature rise in electrical apparatus? 

3. How is the balance tested on small and medium-sized 
machines? 

4. What is the safe-carrying capacity of #5 B&S rubber 
insulated copper wire? 

5. Make a sketch of an enclosed fuse. 

6. Describe the fall-of-potential method for locating faults. 

i. Describe the voltmeter test for insulation resistance. 

8. For what reasons are water-box resistances used? 

9. What is a tachometer? 

10. Calculate the torque of a machine, the horsepower of 
which equals 50 and its speed is 550 revolutions per minute at full 
load. 

11. According to what formula can the mechanical power of 

a generator or motor be calculated? * 

12. Give an expression for the efficiency of a generator and 
for the efficiency of a motor. 

13. In which cases are instrument transformers employed? 

14. Which is the most common trouble encountered with 
dynamo-eleciric machinery? 

15. To what is the humming noise in an alternator due? 

16. What are the general causes for a motor to stop or to 
fail to start? 


466 



GENERAL INDEX 


In this Index the Volume Number appears in Roman numerals—thus 
I, II, III, IV, etc., and the Page Number in Arabic numerals—thus: 1, 2, 3, 4, 
etc. For example: Volume IV, Page 327, is written, IV, 327. 


The page numbers of this volume vnll be found at the bottom of the pages; 
the numbers at the top refer only to the section. 


A 

Absolute pressure. 

Absolute temperature . 

Absorber. 

Absorption system of refrigeration. 

absorber. 

ammonia pump. 

ammonia regulator. 

analyzer. 

care and management. 

charging.. 

condenser. 

economy of. 

efficiency tests. 

equalizer. 

generator. 

operation of. 

power for. 

rectifier... 

Adiabatic compression. 

Aeronautical motors. 

Aftercooler. 

Air brakes. 

air compressors.. 

applied to electric cars. 

brakes and foundation brake gear... 

braking an outgrowth of speed. 

early forms of brake. 

equipment. 

general characteristics of system.... 

modern brake equipment. 

train air-signal system. 

troubles and remedies. 

vacuum brake... 

valves and valve appliances.. 

Westinghouse plain automatic. 

Air compression'... 

at various altitudes. 

compound.. 

power required for.. 

unavoidable losses in. 

Air compressor.. 

compound steam cylinders on. 

Note.—For page numbers see foot of pages. 


Vol. Page 
11,272; V, 12 

. V, 12 

. V, 234 

. V, 226 

. V, 234 

. V, 236 

. V, 239 

. V, 230 

. V, 242 

. V, 244 

. V, 230 

. V, 246 

. V, 245 

. V, 233 

. V, 229 

. V, 239 

. V, 239 

. V, 231 

. V, 17 

. IV, 161 

. V, 132 

.Ill, 205-429 

. Ill, 218 

. Ill, 383 

. Ill, 304 

. Ill, 205 

. Ill, 205 

. Ill, 380 

. Ill, 214 

. Ill, 315 

. Ill, 377 

. Ill, 412 

. Ill, 209 

. Ill, 240 

. Ill, 208 

. V, 19, 94 

. V, 38 

. V, 94 

. V, 37 

. V, 42 

IV, 183; VII, 199 
. V, 5 / 


467 













































9 


INDEX 


Air compressor (continued) 

governors for. 

high-pressure.. 

ignitions and explosions in. 

mechanical efficiency of. 

Air-compressor valves. 

Air-cooled transformers. 

Air cooling, gas engines. 

Air cushion. 

Air distribution. 

Air-filters. 

Air-lift pumps. 

Air machine for refrigerating. 

Air-motor indicator cards. 

Air-power transmission, tables of. . . 

Air strainer and check valve. 

Air-venting. 

Air washer. 

A.L.A.M. rating formula. 

Alberger gas engine. 

Allen cold-air machine. 

Allis-Chalmers gas engine. 

Almy marine boiler. 

Alternating-current controller. 

Alternating-current generators. 

Alternating-current motors. 

polar-wound type. 

repulsion induction motor. 

slip-ring type. 

split-phase type. 

squirrel-cage type. 

synchronous motors. 

Alternators in parallel. 

Altitude gage. 

American locomobile. 

American Thompson indicator. 

Ammonia compressor. 

Ammonia condensers. 

atmospheric. 

Block counter-current. 

double-pipe. 

submerged. 

Vail. 

Ammonia' pump. 

Ammonia receiver.. 

Ammonia regulator. 

Analyzer. 

Anemometer. 

Angle-compound compressors. 

Angle-compound engine. 

Antecooler. 

Arms and hub of drum, design of. . . 

Armstrong hydraulic crane. 

Armstrong three-cylinder machine. . 

Ash-handling apparatus. 

Assembling of machine. 

Atmosphere, definition of. 

Atmosphere condenser. 

Atwater Kent contact maker. 

Automatic air-brake system. 

Note.—For page numbers see foot of pages. 


Vol. 

Page 

V, 

59 

V, 

122 

V, 

118 

V, 

117 

V, 

107 

VII, 

409 

IV, 

249 

VI, 

413 

VII, 

22 

VII, 

204 

I, 

435 

V, 

184 

V, 

144 

V, 

128 

III, 

327 

VII, 

205 

VII, 

205 

IV, 

157 

IV, 

126 

V, 

220 

IV, 

131 

I, 

152 

VI, 

189 

VII, 

265 

VII, 

274 

VII, 

280 

VII, 

285 

VII, 

281 

VII, 

283 

VII, 

274 

VII, 

289 

VII, 

269 

VII, 

114 

II, 

55 

II, 

238 

V, 

243 

V, 289, 343 

V, 

293 

V, 

300 

V, 

298 

V, 

290 

V, 

304 

V, 

236 

V, 

325 

V, 

239 

V, 

230 

VII, 

21 

V, 

87 

II, 

49 

V, 

131 

VI, 

253 

VI, 

93 

VI, 

107 

I, 

252 

VII, 

237 

■ V, 

12 

V, 

293 

IV, 

213 

III, 

384 


468 






























































INDEX 


3 


Automatic brake operation. 

Automatic brake valves. 

Automatic clearance. 

Automatic control of pumps. 

Automatic controller valve. 

Automatic gate. 

Automatic return pumps. 

Automatic skimmer systems. 

Automatic slack-adjuster. 

Automatic steam valve. 

Automatic stop. 

Automatic stop and check valves.. 

Automobile engines. 

Auxiliary devices.. 

Auxiliary reservoir. 

Axle-driven compressor equipment 
Axles. 


11 

“B-6” double-pressure feed valve. 

B-valve. 

Babcock and Wilcox boiler. 

Babcock and Wilcox marine boiler. 

Balance pipe. 

Baldwin superheater. 

Ball valves. 

Bar channelers.. 

Barometers. 

Barometric condenser. 

Barr strainer. 

Barrel calorimeter. 

Basement elevator. 

Batch filtration lubrication systems. 

Batteries, ignition. 

Beam arrangement. 

Beam sizes, selection of. 

Bearing boxes. 

Bearing pressure. 

Beco-Diesel engine. 

Bell-cord signals. 

Belpaire boiler. 

Belt-driven compressors. 

Belt-driven elevators. 

calculation of belt size. 

calculation of belt width. 

calculation of horsepower required . 

effect of counterbalance weight. 

factors in belt selection. 

high-duty belts required. 

single-belt electric elevators. 

transmission stress in belt. 

Belt-driven pumps. 

Belt power elevators. 

Belt selection, factors in. 

Belt shippers. 

braking means.. 

cylindrical and disk types. 

early type.. 

Belt size, calculation of. 

Note.—For page numbers see foot of pages. 


Vol. Page 
. Ill, 332 

III, 240 
V, 70 
I, 438 
V, 111 
. VI, 397 

. VII, 140 

1, 219 

. Ill, 309 

. VI, 84 

. VI, 390 

I, 193 
. IV, 139 

. VI, 119, 151 
. Ill, 215 

. Ill, 409 

III, 115, 133 


. . . . Ill, 258 
I, 442 
I, 113 
I, 149 
. . . . VII, 141 
. . . . Ill, 80 

I, 399 
.... V, 166 

.... II, 199 

.... II, 142 

I, 463 
1, 347 

.... VI, 37 

... II, 180 

.... IV, 197 

.... VI, 294 

.... VI, 300 

VI, 266, 268, 269 
.... VI/ 267 

. . IV, 177 

.... Ill, 159 

1, 101 
.... V, 46, 61 

.... VI, 358 

.... VI, 359 

.... VI, 361 

.... VI, 358 

... VI, 358 

.... VI, 360 

.... VI, 361 

.... VI, 362 

.... VI, 360 

1, 425 

.... VI, 48-64 

.... VI, 360 

.... VI, 61 

. VI, 63 

. VI, 62 

. VI, 61 

. VI, 359 


469 



























































4 


INDEX 


Belt width, calculation of. 

Belting. 

Belts. 

Bigelow-Hornsby boiler. 

Blake pump valve. 

Blast-furnace gas. 

Block counter-current condenser... 

Block system of signaling. 

Blow-off cocks. 

Blow-off pipe. 

Blow-off tank. 

Blow-off valve. 

Blower. 

Boiler accessories. 

ash-handling apparatus. 

blow-off pipe. 

brackets.. 

breechings . 

chimneys. 

coal handling apparatus. 

columns. 

damper. 

draft apparatus. 

feed apparatus. 

feed pump. 

fuel economizers. 

furnace fittings. 

fusible plugs. 

gage cocks. 

gage glasses. 

handholes. 

heaters. 

high- and low-water alarms 

iniector. 

lagging. 

lugs... 

manholes. 

masonry. 

pressure gage. 

pumps. 

safety valve. 

soot blowers. 

ste$,m gages.. 

steam piping.. 

steam separators. 

superheaters. . . . . 

supports. 

tools. 

traps. 

try cocks. 

valves. 

water columns. 

water gage. 

Boiler action, essential principles of. 

Boiler circulation. 

Boiler cleaning. 

Boiler connections. 

Boiler construction. 

allowable pressure. 

Note.—For -page numbers see foot of pages. 


Vol. 

Page 

.. VI, 

361 

.. VII, 

231 

71, 49, 61, 

361 

I, 

136 

I, 

447 

.. IV, 

64 

V, 

94 


I, 

191 

I, 

72 

.. VII, 

78 

I, 

192 

III, 

154 

I, 71, 169 

-255 

I, 

252 

I, 

72 


72 


246 

I, 72, 

238 

I, 

249 


72 


72 


237 


200 


71 


247 


72 

I, 72, 

174 


71 


180 


169 


72 

I, 

72 


207 


233 


72 

. I, 72, 169 


72 


72 


205 


72 


230 

I, 

176 

I, 72, 

196 


224 


220 


172 


72 

I, 

227 

I, 

182 

I, 

183 

I, 

179 

I, 

71 

I, 

11 

I, 

155 

I, 

160 

. VII, 

77 

I, 11 

-68 

I, 

66 


470 





























































INDEX 


Boiler construction (continued) 

area of grate.. 

calking. 

expanding tubes, methods of. 

flanging. 

flues. 

furnace flues. 

heating surface. 

manholes. 

materials. 

plates and joints, arrangement of 

rating. 

requirements. 

riveted joints. 

sections. 

shaping butt straps. 

stays. 

steam space. 

tubes.... 

water-leg construction. 

welded joints. 

Boiler coverings. 

Boiler design. 

accessibility. 

circulation. 

plant features influencing design. 

shapes and sizes of tubes. 

Boiler explosions. 

boiler inspection. 

causes. 

, energy developed. 

investigation. 

nature of. 

prevention. 

Boiler functions. . ... 

Boiler horsepower. 

Boiler inspection. 

Boiler materials. 

brass. 

bronze. 

cast iron. 

copper. 

steel.. 

tests of. 

Boiler performance... 

Boiler practice. 

Boiler pressure.. 

Boiler settings.. 

Boiler supports. 

Boiler test code, abstract of. 

Boiler tests. 

Boiler tubes. 

Boiler types.. 

classification. 

early forms. 

fire-box. 

fire-tube. ; . 

internally-fired marine. 

marine... 

modern flue boilers. 

< Note.—-For page numbers see foot of pages. 


Vol. Page 

. I, 62 

. 1, 35 

. I, 57 

. I, 29 

. I, 52 

. I, 59, 67 

. I, 65 

. I, 43 

I, 12 

. I, 37 

I, 63 

. I, 60 

. I, 25, 30 

. I, 67 

. 1, 29 

. 1, 44 

. I, 64 

. I, 52 

. I, 38 

. I, 36 

. I, 236 

. I, 155 

. I, 160 

. I, 155 

. I, 163 

. I, 162 

. I, 328 

. I, 329 

. I, 331 

. I, 330 

. I, 334 

. I, 329 

. I, 335 

. I, 71 

. Ill, 90 

. .1, 67, 160, 329 

. I. 12 

. I, 14 

. I, 14 

. I, 12 

. I, 14 

. I, 13 

. I, 14 

. Ill, 71 

. I, 257-365 

. II, 272 

I, 257; VII, 388 

. I, 172 

. I, 358 

.... 1, 355 

. I, 52 

. I, 71-166 

I, 73 

. I, 75 

. I, 75, 99 

. . I, 75, 84, 155 

. I, 92 

. I, 144 

. I, 79 


471 





























































6 


INDEX 


Boiler types (continued) 

peculiar forms. 

water-tube. 

Boilers. 

boiler setting.-. 

care of. 

classification. 

economic. 

fire-tube. 

Galloway. 

marine. 

water-tube. 

deterioration of. 

draft... 

efficiency. 

feed water. 

feeding appliances. 

firing of. 

floor space.... 

initial cost. 

steam piping. 

superheated steam.:. 

Boilers, steam heating, care and management of 

Bottom blow-out. 

Bourdon dial gage. 

Boyle’s law. 

Brady Scotch boiler. 

Brake cylinder. 

Brake horsepower. 

Brakes. 

Brakes and foundation brake gear. 

Branca’s impulse turbine. 

Brass. 

Breechings. 

Brick arches. 

Bridge — .... 

Brine agitators. 

Brine cooler. . 

Brine tank. 

Brine tests. 

British thermal unit. 

Bronze. 

Bronze gear. 

Brown releasing gear. 

Bruce-MacBeth gas engine. 

Brumbo pulley. 

Buckeye engine test. 

Buckeye shaft governor. 

Buckeye valve gear. 

Buckeye vertical cross-compound engine. 

Buffalo Forge Spiro turbine. 

Buffers and bumpers. 

Busch-Sulzer atomizer. 

Busch-Sulzer oil engine. 

Buttom end-thrust blocks. 

Burhorn cooling tower. 


C 

“C-6” single-pressure feed valve. 

Cable guard. 



Vol. Page 
I, 104, 142 


, 75, 109, 

156 , 

. VII, 

374 . 

. VII, 

388 

I, 

316 

. VII, 

375 

.. VII, 

376 

. VII 

375 

. VII, 

376 

. VII, 

376 

VII, 

376 i 

VII, 

377 

. VII, 

388 

. VII, 

377 

. VII, 

385 

. VII, 

386 

. VII, 

389 

. VII, 

377 

VII, 

377 

. VII, 

379 

. VII, 

384 

. VII, 

102 

I, 

218 

I, 

176 

V, 

14 

I, 

106 

III, 215, 

403 

II, 

278 

. VI, 28, 

410 

. Ill, 

304 

IV, 

361 

I, 

14 

I, 72, 

246 

III, 

63 

II, 

354 I 

V, 

372 

V, 

318 

V, 

314 

V, 

321 

!; VII, 

23 

I, 

14 

VI, 

70 

II, 

410 

IV, 

123 

II, 

251 


212 

II, 

157 

II, 

401 

II, 

46 

• IV, 

475 


414 

• IV, 

98 

IV, 

170 

• VI, 

73 

• V, 

311 

III, 

255 

• VI, 

120 


Note.—For page numbers see foot of pages. 


472 




























































INDEX 


7 


Cable safeties. 

Cables. 

Cabs. 

Cage construction. 

Cahall boiler. 

Calking. 

Calorimeters. 

Calorimetric measurements. 

Cameron belt-driven pump. 

Cameron steam valve. 

Can ice plant. 

Cantilever function. 

Capitaine underfeed gas-producer 

Car discharge valve. 

Car guards. 

Car guides. 

Car inclosures. 

Car lifting connections. 

Car-locking device. 

Car safeties. 

Car signals. 

Carbon dioxide. 

Carbon dioxide refrigerating machine 

Carbon monoxide. . 

Carbureters. 

bubbling. 

spray.. 

surface. 

types. 

Carels-Diesel engine. 

Carre absorption machine. 

• Cast iron. 

Cast-iron plunger. 

Cast-iron spur gears, pitch of. 

Cast-iron worm gears, pitch of. 

Center-lift hand elevator. 

f Center line. 

' Centering line. 

Centrifugal fans. 

"Centrifugal pumps. 

characteristics. 

curve of the blades an involute.. 

operation. 

speed. 

staying. 

types. 

turbine. 

volute. 

whirlpool. 

Centrifugal safety devices. 

Centrifugal tar extractor..... 

Chain grate stoker. 

Chapman gas-producer. 

Gharles’ law. 

Charter vaporizer. 

Check valve.. 

Cheek plates for stiles.. 

Chemical elements in cast iron 
‘Chimney flues. 


Vol. Page 

. VI, 389 

.VI, 270, 389 

. VI, 401 

. VI, 321 

. I, 131 

. I, 35 

I, 347; II, 199, 308 

. II, 287 

. II, 78 

. I, 444 

. V, 356 

. VI, 250 

. IV, 308 

. Ill, 380 

. VI, 403 

. VI, 284 

. VI, 401 

. VI, 327 

. VI, 410 

. VI, 380 

. VI, 403 

. IV, 52 

. V, 281 

. IV, 52 

. IV, 74 

. IV, 74 

. IV, 75 

. IV, 74 

. IV, 74 

. IV, 174 

. V, 226 

I, 12 

. VI, 157 

. VI, 245 

. VI, 247 

. VI, 24 

. VI, 60 

. VI, 391 

. VII, 169 

. I, 208, 380 

. I, 387 

. I, 381 

. I, 388 

. I, 383 

. I, 386 

. I, 384 

. I, 386 

. I, 385 

. I, 384 

. VI, 50 

. IV, 339 

. Ill, 131 

. IV, 322 

. V, 15 

. IV, 90 

. I, 186, 462 

. VI, 323 

. VI, 252 

. VII, 38 


Note.—For page numbers see foot of pages. 


473 





























































8 


INDEX 


Chimneys.•*. 

Circuit-breakers. 

Circuit system of piping. 

Circulation coils. 

Clearance.•. 

Coal gas. 

Coal-handling apparatus.... 

Coal-mining machines. . 

Cochrane boiler. 

Coke-oven gas. 

Cold-air box. 

Cold-air ducts. 

Cold storage... 

Cole superheater. 

Collapsible gates. 

Collar end-thrust blocks. 

Collisions. 

Combined-condenser pumps. 

Combustion, rate of. 

Combustion chamber. 

Commercial storage. 

handling goods. 

removal of stores. 

separation of products. 

storage rates. 

sudden changes in temperature. 

Commercial turbines. 

Commutation-pole motors. 

Compensator used with counterpoise. 

Compound air-compression. 

Compound engines. 

Compound impulse turbines. 

Compound locomotive.... 

Compound pumping engine. 

Compound steam pump valves. 

Compressed air. 

Compressed-air appliances. 

bar chambers. 

coal-mining machines. 

compression riveters and pneumatic punches 

electric-air principle. 

electro-pneumatic switch and signal system. 

hammer drill. 

pneumatic hammers. . 

pneumatic haulage. 

pneumatic hoists. 

pumping by compressed-air. 

rock drill. 

rotary pneumatic drills. . 

sand blast. 

track channelers. 

undercutting track channelers. 

Compressed-air pumps. 

Compression.. 

adiabatic.*. 

cooling during. 

heating effect of. 

necessity for cooling during. 

phenomena of.. 

Note.—For page numbers see foot of pages. 


Vol. 

Page ; 

I, 

238 


306 

. VII, 

128 ; 

. VII, 

55 

• II, 

123 

IV, 

62 

I, 

249 

V, 

158 

I, 

105 

• IV, 

64 

VII, 

38 

. VII, 

92 

V, 

418 

. Ill, 

77 ■ 

VI, 

401 

. vi; 

74 :] 

. Ill, 

188 

I, 

427 

III, 

69 

. VII, 

34 ; 

V, 

448 

V, 

448 1 

V. 

450 ! 

• V, 

451 

• V, 

454 : 

v, 

450 

IV, 

413 

VII. 

263 

VI, 

338 

V, 

94 

II, 

36 

• IV, 

436 

. Ill, 

30 

II, 

17 

I, 

451 

. V, 11-181 

V, 

150 

V, 

166 

V, 

158 

V, 

170 

• V, 

177 

• V,' 

179 

• V, 

154 

• V, 

168 

V, 

180 i 


170 

• V, 

170 

V, 

151 ! 

V, 

168 

V, 

170 


160 

• V, 

164 


431 


15, 91 


17 


91 

V, 

20 

• V, 

18 


16 


474 

































































INDEX 


9 


Compression (continued) 

pressure and volumes in. 

Compression tank. 

Compressor losses. 

Compressor piston. 

Compressor types, classification of. 

Compressor valves. . 

Compressors, refrigeration. 

Condensation effect of. 

Condenser, use of. 

Condenser action, theory of. 

Condensers. 

Conduction of heat. 

Conductor’s valve. 

Connecting or main rods. 

Connections of machine. . .. 

alternating-current generators. 

alternating-current motors. 

direct-current constant-potential motors 

direct-current generators. 

synchronous converters. 

three-wire system. 

Connelly boiler. 

Construction of boilers.. 

Control-circuit safety devices. 

Control valve. 

Controllers, elevator. 

Convection of heat. 

Cooling, gas engine. 

Cooling, methods of. 

Cooling coils. 

Cooling during compression. 

Cooling towers. 

Copper. 

. Corliss engine. 

Corliss regulators. 

Corliss valve gear. 

Corner-post hand elevator. 

Cornish boiler. 

Corrosion. 

Cotter. 

Counterpoise cable attachment. 

Counterpoise car. 

Counterpoise in electric elevators. 

Counterpoise guides. 

Counterpoise weights,. 

Counterpoising. 

Crane limit valve. 

Crane operating-lever device. 

Crane valve.. . . .^. 

Crank effort. 

Crank pins. 

Crawford mechanical underfeed stoker. 

Crosby indicator. 

Crosby reducing wheel. 

Crossbeams. 

Cross-compound engine. 

Crosshead.. 

Crosshead and connecting rod. 

Crossheads and guides. 


Vol. Page 

. V, 17 

. VI, 128 

. V, 286 

. V, 260 

. V, 46 

. V, 254 

.V, 251, 275 

. II, 135 

. IV, 211 

. II, 135 

...11,135; V, 230 

. V, 202 

.Ill, 298, 403 

. Ill, 124 

. VII, 240 

. VII, 265 

. VII, 274 

. VII, 257 

. VII, 240 

. VII, 247 

. VII, 254 

. I, 138 

. I, 11-68 

. VI, 408 

. Ill, 351 

. VI, 186 

. V, 201 

. IV, 249 

. V, 436 

. V, 368 

y 9i 

’.V U, 147; V, 307 

. I, 14 

. II, 47 

. V, 71 

. II, 406 

. VI, 34 

.1.79; VII, 375 

. I, 319 

. VI, 352 

. VI, 337 

. VI, 336 

. VI, 376 

. VI, 285 

VI, 26, 163, 220, 331 

. VI, 331 

. VI, 125 

. VI, 134 

. VI, 88 

. II, 151 

.Ill, 116, 137 

. Ill, 132 

. II, 233 

. II, 256 

. VI, 324 

II, 37 

.VI, 352, 354 

. II, 29 

. Ill, 122 


Note. —For page numbers see foot of pages. 


475 





























































10 


INDEX 




Vol. Page 

Crossley gas-producer.^’jy 02 ’ 318 

ml pn(rinp . .? 


168 


Cut-off. 


Cylinders. 

Cylindrical boilers. 


D 


D-valve. 


Dampers. 


Deflector. 


Design of elevators (see equipment design and construction 


Direct hot-wat< 
Direct-indirect 


... vi, 

313 . 

... IV, 

66 

. . IV, 428, 

459 

• ■ • VI, 

413 

.. . II, 

354 


343 

... VI, 

349 

II, 

39 

20; III, 

141 

... I, 

77 

... VI. 

62 

... Ill, 

402 

.. Ill, 

393 

... I, 

440 

... I, 

72 

VII, 

144 

.. VII, 87, 

202 

• ■ I, 

448 

... v, 

270 

... VI, 

292 

I, 

446 

I, 

446 

... IV, 

337 

414, 434, 

450 

... iv, 

163 

III, 

189 

ot 


. . .VI, 233- 

-415 

... VII, 

377 

... HI, 

64 

... VII, 

202 

... VII, 

201 

... IV, 

36 

. IV, 

182 

.. . IV, 17, 

170 

423; V, 

171 

.. . VI, 

‘242 

... VI, 

90 

... VI, 

187 

... VII, 

240 I 

... VII, 

245 

... VII, 

241 

... VII, 

242 

... VII, 

244 '! 

... VII, 

240 

... VII, 

240 1 

... VI, 

379 

... V, 

175 

... VII, 

31 

...VII, 14, 

107 

...VII, 14, 

101 

. . . VI, 

156 

... VI, 

171 

... VI, 

163 

... VI, 

159 


Note.—For page numbers see foot of pages. 


476 




























































INDEX 


11 


Direct-plunger hydraulic types (continued) 

electric control. 

general construction. 

limit devices. 

operating chain and ring. 

operating valve.. 

plunger. ... .. 

plunger stays. 

trapdoor arch. 

traveling stay. 

Direct shaft connected compressors. 

Direct steam heating. 

! Directum boilers. 

Disc or propeller fans. 

Disc-valve opening. 

Distilling apparatus. 

Domestic dumb-waiter. 

Doors for shafts. 

door opening horizontally. 

Meeker self-closing door. 

type opening vertically. 

Double-duct system of heating. 

Double-ended boiler. 

Double-pipe condenser. 

Double-pointed air gage. 

Double-threaded worm. 

Double-tube boiler, definition of. 

Draft. 

mechanical. 

natural. 

! Draft gages. 

Draft pipes. 

Drafts, natural and forced. 

Drawbars. 

Drum. 

influence of. 

winding of. 

Drum barrel, designing of. . 

Drum and cables. 

Drum extension for annular gear. 

Drum governor. 

Drum shafts, design of. 

belted electric elevators. 

direct-connected electric elevators. 

hand power elevator. < . 

two-belted machines. 

Drum size in electric elevators. 

Dry pipe. 

Dry-plate system. 

Dry-vacuum pumps. 

Dudgeon expander. 

Dumb-waiter. 

domestic type. 

heavy-service type. 

medium load type. 

Duplex air-compressor. 

Duplex air gage. 

Duplex pumps. 

Duty of pump. 

Note.—For page numbers see foot of pages. 


Vol. 

Page 


173 

.. vi; 

156 


167 

.. VI, 

162 

.. VI, 

171 

.. VI, • 

157 

.. VI, 

166 

.. VI, 

163 

.. VI, 

165 



2, 52 


108 

.. VII, 

181 

. .. VI, 

346 

V, - 

358 

. VI, 

43 

.. VI, 

394 

. VI, 

395 

. VI, 

394 

. VI, 

394 

. VII, 

16 

. . I, 95, 

147 

V, 

298 

. Ill, 

215 

. . VI, 68, 

216 

I, 

75 

64; VII, 

388 

. VII, 

389 

. VII, 

388 

. I, 305, 

450 

. Ill, 

64 

I, 

237 

VI, 

328 

VI, 236, 

253 

VI, 

236 

VI, 

253 

• VI, 

254 

VI, 219, 

223 

VI, 

254 

VI, 

51 

VI, 

236 

VI, 

239 

VI, 

242 

. VI, 

236 

VI, 

238 

VI, 

375 


155 

V, 

386 

I, 

429 

I, 

58 

VI, 

42 

■ VI, 

43 

• VI, 

45 

• VI, 

45 

V, 55, 82 

III, 255, 

420 


417 


472 


477 































































12 


INDEX 


Dynamo-electric machinery, management of (see management 
dynamo-electric machinery). 


of 


Vol. Page 


J 


.VII, 225-346 


E 

“E-6” safety valve. .......... 

Early New England low-pressure hydrauhc elevator 

Eccentric. 

Eccentric-cam grip. 

Economic boiler. 

Edge Moor boiler. 

Efficiency meter.. 

Electric-air principle. 

Electric-car air brakes..*. 

Electric-car brake equipment. 

Electric control. 

Electric elevator control.. 

car-locking device.. 

control-circuit devices. 

operating-circuit devices. 

Electric elevators. 

control.. . 

difficulties with variable speeds. 

early types.. 

miscellaneous elevators. 

motor design. 

power for. 

traction elevators. 

transmission. 

Electric engine, location of. 

Electric heat and energy. 

Electric heaters. 

calculation of.. 

connections for. 

construction of... 

Electric heating. 

Electric ignition. 

Electric motors.. . 

Electric plant. 

capacity. 

efficiency. 

excitation..’. 

generators. 

mechanical features. 

air-cooled transformers. 

oil-cooled transformers. 

storage batteries. 

transformers. 

water-cooled transformers. 

speed and regulation. 

types.. 

Electric tachometer. 

Electrical power. 

Electrical quantities. 

Electro-pneumatic switch and signal system. 

Elevator cars. 

cage construction. 

counterpoising. 

essential elements... 

platforms. 

Note.—For page numbers see foot of pages. 


.. Ill, 

302 

.. VI, 

102 

. . 11, 28, 

322 

.. VI, 

382 

.. VII, 

376 

I, 

119 

I, 

307 

V, 

177 

III, 383, 

426 

. . Ill, 

385 

.. VI, 

173 

.. VI, 

408 

.. VI, 

410 

.. VI, 

408 

.. VI, 

409 

..VI, 177- 

-231 

. VI, 

185 

.. VI, 

179 

.. VI, 

177 

• VI, 

231 

.. VI, 

180 

.. VI, 

374 

.. VI 

221 

.. VI, 

209 

.. vi; 

209 

.. VII, 

196 

.. VII, 

196 

. VII, 

197 

.. VII 

197 

. VII, 

196 

. VII, 16, 

196 

.. IV, 

189 ' 

.. VI, 

58 

.. VII, 

404 

.. VII 

405 

. VII, 

•406 

.. VII, 

407 

.. VII, 

404 

. VII, 

408 

.. VII 

409 

.. VII, 

410 

.. VII, 

412 

.. VII, 

408 

.. VII, 

411 

.. VII, 

408 

.. VII, 

405 

VII, 

322 

.. VII, 

325 

. VI, 

378 

V, 

179 

.. VI, 

300 

... VI, 

321 

... VI, 

331 

... VI, 

300 

... VI, 

302 


478 




























































INDEX 


13 


Elevator equipment design and construction 

elevator cars. 

hydraulic parts. 

proportioning simple parts. 

safety devices. 

supporting structure. 

transmission parts. 

Ellis and Eaves system of forced draft. 

Emergency switch. 

Empirical disign. 

End-thrust blocks. 

ball-bearing type. 

button type. 

collar type. 

loose-ring type. 

steel-plug type. 

End-thrust of worm shaft. 

Engine design. 

axles. 

crank pins. 

cylinders. 

frames. 

piston rods. 

Engine mechanisms, analysis of. 

Engine specification. 

Engine tests. 

Engines and their operation, cost of. 

Equalizer.. 

Erection of machine. 

assembling... 

belting... 

direct connection. 

fixing machine. 

foundations. 

location. 

rope driving. 

shafting... 

toothed gearing.. 

Erie City boiler... 

Evaporators.. 

Excitation generators. 

Exhaust. 

Exhaust head.*. 

Exhaust nozzle. 

Exhaust port... 

Exhaust-steam heating. 

Exhaust valve. 

Exhaust waste. 

Expanders.. 

Expansion, cooling by. . 

Expansion coils. 

Expansion tank. 

Explosion, cause of...: . 

External-combustion motors. 

Externally-fired boiler. 

Extra-squeeze brake.. 


Fans 


F 


Vol. Page 

. .. VI, 233- 

-415 

.... VI, 

300 

.... VI, 

341 

.... VI, 

233 

.... VI, 

380 

.... VI, 

279 

... VI, 

244 

... 1, 

244 

.... VI, 

409 

.... VI, 

234 

.... VI, 

73 

.... VI, 

77 

.... VI, 

73 

... VI, 

74 

.... VI, 

77 

.... VI, 

76 

.... VI, 56, 

217 

.... Ill, 

133 

.... Ill, 

133 

.... Ill, 

137 

.... Ill, 

141 

.... Ill, . 

140 

.... Ill, 

139 

.... II, 

151 

.... II, 

185 

.... II, 

193 

.... II, 

190 

.... V, 

233 

.... VII, 

226 

.... VII, 

237 

.... VII, 

231 

.... VII, 

229 

.... VII, 

228 

.... VII, 

226 

.... VII, 

226 

.... VII, 

235 

.... VII, 

237 

.... VII, 

236 

1, 

139 

1, 213; V, 

313 

.... VII, 

407 

.... IV, 

254 

.... VII, 

140 

.... Ill, 63 

!, 66 

.... II, 

354 

. . . VII, 15, 

134 

.... IV, 

250 

.... II, 

122 

.... I, 

57 


121 

.... V, 

370 


113 

.... I, 

331 

.... IV, 

11 

.... I, 

75 


410 

. VII, 

169 


Note.—For page numbers see foot of pages. 


479 





























































14 


INDEX 


Fans (continued) 

centrifugal. 

disc or propeller. 

electric motors for. 

engines for. 

Fairbanks-Morse carburetor. 

Fairbanks-Morse suction gas-producer 
Fairbanks-Morse vertical gas engine. 

Feed apparatus.. 

Feed pump. 

Feed valves. 

Feed water... 

Feed-water connections. 

Feed-water heater. 

Feed-water regulators. 

Feed-water temperature. 

Feeding appliances.. 

Fensom balancing device. 

Fiber stresses, safe. 

“Fifty-four” air strainer. 

Filters... 

“Finger” valve action. 

Fire-box. 

Fire-box boiler. 

Firepot. 

Fire pumps. 

Fire-tube boilers. 

circulation in.. 

definition of. 

fire-box. 

horizontal.. 

internally-fired marine. 

peculiar forms. 

vertical.. 

Firing by hand. 

Firing a locomotive. 

Fixed signals. 

Flanging. 

Flexible valves.. 

Flooded system of refrigeration. 

Floor thimbles and rope guides. 

Flues. 

Fly-ball governor. 

Flywheel. 

Foos gas engine. 

Forced blast. 

cast-iron heaters, efficiency of . . . . 

double-duct system. 

ducts and flues, area of. 

factory heating. 

fan engines. 

fans. 

heating surface, form of. 

pipe-heaters, efficiency of. 

plenum method. 

Forced-blast heating. 

Forced hot-water circulation. 

Foster superheater. 

Four-chain basement elevator. 

Frick ice plant. 

Note.—For page numbers see foot of pages. 


Vol. 

Page 

VII, 

169 

VII, 

181 

VII, 

187 

VII, 

185 

IV, 

86 

IV, 

298 

IV, 

125 

I, 

200 

I, 

71 

■; iv, 

344 

VII, 

385 

I, 

201 

1 ; II, 

151 

I, 

211 

II, 

286 

VII, 

386 

VI, 

107 

VI, 

356 

III, 

228 

V, 

368 

V, 

113 

III, 

48 

I, 

75, 99 

VII, 

33 

I, 

418 

VII, 

375 

I, 

155 

I, 

75 

I, 

75, 99 

I, 

84 

I, 

92 

I, 

104 

I, 

88 

1 , 

268 

III, 

169 

III, 

164 

I, 

29 

I, 

396 

V, 

339 

VI, 

31 

III, 

' 53 

II, 

161 

II, 

152 

IV, 

128 

VII, 

157 

VII, 

167 

VII, 

193 

VII, 

188 

VII, 

189 

VII, 

185 

VII, 

169 

VII, 

158 

VII, 

162 

VII, 

158 

VII, 

16 

VII, 

127 

II, 

129 

VI, 

37 

V, 

378 


480 






























































INDEX 


15 


Frick refrigerating machinery. 

Friction. 

Friction safety. 

Fuel burning, general features of. 

Fuel ecmiorni7.Prs 

Vol. 

. V, 

. II, 

. VI, 

.-. I, 

. I. 

Page 

279 

123 

384 

289 

247 

Fuel mixing devices... 

Fuel waste in a locomotive. 

Fuels, heat value of. 

Fuels and fuel mixtures for gas engines. 

Fulton-Tosi atomizer. 

Fulton-Tosi oil engine. 

Furnace fittings. 

Furnace flues 

. IV, 72 

. Ill, 186 

. I, 337 

.IV, 51, 258 

. IV, 99 

. IV, 170 

. I, 72 

. I, 59, 67 

Furnaces. 

care and management of. 

.I, 261, 289; VII, 

. VII, 

. VII, 

11, 29 
44 
38 

pnlrl-fur noY . 

. VII, 

38 

nnmV'iinfi fir>n tjvstpms 

. VII, 

43 

r»nmhiiQtinn pViamnpr . . 

. . VII 

34 


. I, 

263 


. I, 

274 


. VII, 

35 


. VII, 

33 


.1, 263 ; VII, 

32 


. I, 275, 291 


. I, 

. VII, 

261 

36 


. VII, 

. VII, 

35 

37 


. I, 

276 


. VII, 

34 



43 


. VII, 

39 


. I, 

273 


. VII, 

37 


. VII, 

30 


. VII, 

40 


. VII, 

308 


Fusible plug 


V, 

. Ill, 

240 

(jr-b automatic Draxe vaive. 

. I, 

71 



180 



308 



376 

336 





124 



58 



273 

277 



adjustment of point of ignition. 

. IV, 

277 



282 

carbureter adjustments... 


279 

car and adjustment oi ignition systems. 

. IV, 

273 

classification of troubles. 


276 



283 

276 

fitting piston rings.. 


investigating quality oi mixture . 

method of locating seat of trouble. 

. IV, 

275 


Note,—For page numbers see foot of pages. 


481 



























































INDEX 


10 


Gas-engine operation (continued) 

stoppage of jacket water. 

Gas and oil engines. 

aeronautical motors. 

automobile engines. 

classification of heat engines. 

design data. 

Diesel oil engines. 

engine details. 

external-combustion motors. 

fuel mixing devices. 

fuels and fuel mixtures. 

gas cleaners. 

high-speed type. 

horizontal type.'. 

ignition systems. 

injection-air supply.. 

internal-combustion motors. 

low-pressure oil engines.. 

marine engines. 

Otto-cycle gas engine. 

performance data. 

thermodynamics of internal-combustion cycles 

Gas plant. 

Gas poisoning. 

Gas producers.... 

balanced-draft type. 

care of gas engines and producers. 

chemical action in. 

comparison between producer gas and steam.. 

details of.. 

fire-brick lining. 

gas-cleaning. 

history of producer gas. 

manufacture of producer gas. 

pressure type. 

producer gas and its competitors. 

producer-plant tests, results of. 

regulation of steam supply. 

suction type. 

types of. 

working of. 

Gases, physical properties of. 

Gasketed joints. 

Gate valve. 

Gear arms, design of. 

Gear parts, design of. 

Gear pitch, determination of. 

Gear rim, design of. 

Gear tooth construction.. !.’ ’ * 

Gearing. ’ ’ 

Gears and cables in electric elevators. 

Generators. 

Globe valve. 

Gooch link. ’ 

Governor actuation of friction safety. 

Governors. 

air pump.. . 

gas engine. 

steam engine. 

Note.—For page numbers see foot of pages. 


Vol. 

Page 

IV, 

277 

IV, 11 

-283 

IV, 

161 

IV, 

139 

IV, 

11 

IV, 

258 

IV, 

170 

IV, 

225 

IV, 

11 

IV 

72 

IV, 

51 

IV, 

138 

IV, 

139 

IV, 

125 

IV, 

187 

IV, 

183 

IV, 12, 

105 

IV, 

163 

IV, 

159 

IV, 

106 

IV, 

269 

IV, 

18 

VII, 

402 

IV, 

354 

IV, 285 

-354 

IV, 

327 

IV, 

352 

IV, 

290 

IV, 

341 

IV, 

331 

IV, 

331 

IV, 

336 

IV, 

286 

IV, 

287 

IV, 

314 

IV, 

285 

IV, 

348 

IV, 

332 

IV, 

298 

IV, 295, 

328 

IV, 

291 

IV, 

52 

I, 

199 

I, 

185 

VI, 

250 

VI, 

249 

VI, 

245 

VI, 

249 

VI, 

70 

VI, 48, 

244 

VI, 

376 

vii, 

404 

I, 

184 

II, 

383 

VI, 

384 


Ill, 215, 234, 414 
■ ... IV, 225 
.. . . II, 158 


482 






























































INDEX 


Governors on compressors. . . 

Grate area for boilers. 

Grates. 4 ... 

Gravity hot-water circulation 

Grease extractor. 

Green fuel economizer. 

Greene drop cut-off gear. 

Guards on elevator car. 

Gudgeons, size of. 

Gudgeons and track rails.... 

Guide oilers. 

Guidepost. 

Guide shoes. 

Guideway construction. 

speed factor. 

Gunboat boiler. 


Vol. Page 

. V, 59 

. I, 62 

I, 263; III, 60; VII, 32 

'.. VII, 108 

. VII, 137 

. I, 247 

. II, 411 

. VI, 318 

. VI, 235 

. VI, 354 

. VI, 415 

.VI, 18, 279, 280 

. VI, 329 

. VI, 279 

. VI, 279 

. I, 147 


II 

“H-6” automatic brake valve. 

Hackworth gear. 

Hale hemp piston packing. 

Hale standard hydraulic. 

Hale valve. 

Hale water-balance elevator. 

Hamilton-Holzwarth turbine. 

Hammer drill.. 

Hand brakes on electric cars. 

Handholes. . 

Hand-power elevators. 

design of drum shafts for. 

historical development. 

modern hand type. 

power for. 

special types. 

Hanna locomotive stoker. 

Harrison boiler. 

Hart cooling tower. 

Hartman’s compound impulse turbine. .*. 

Hatch switches. 

Haystack boiler. 

Hazleton boiler. 

Head of water. . 

Heat efficiency of boilers. 

Heat loss from buildings. 

Heaters. 

efficiency of. 

types of. 

Heating surface.. 

Heating surface of boilers. 

Heating systems. 

direct hot-water... 

direct-indirect radiators. 

direct steam. 

electric heating. 

exhaust steam. 

forced blast. 

furnaces. 

indirect hot-water. 

indirect steam. 

Note.—For page numbers see foot of pages. 


. Ill, 249 

. II, 384 

. VI, 110 

. VI, 107 

. VI, 109 

. VI, 104 

. IV, 446 

. V, 154 

. Ill, 383 

.I, 44, 72, 169 

. VI, 11-47 

. VI, 236 

. VI, 11 

. VI, 16 

. VI, 357 

. VI, 33 

. Ill, 131 

. I, 143 

. V, 309 

. IV, 365 

. VI, 223 

. I, 75 

. I, 142 

.VI, 369, 370 

. VII, 377 

. VII, 23 

I, 72; VII, 132 

. VII, 84 

. VII, 82 

. Ill, 73 

. I, 65 

. VII, 11 

. VII, 14 

. VII, 14 

. VII, 12 

. VII, 16 

. VII, 15 

. VII, 16 

.... VII, 11 

. VII, 15 

. VII, 13 


483 



























































18 


INDEX 


Heating systems (continued) 

stoves... 

Heating and ventilation. 

air-filters and air-washers.. 

care>nd management of boilers. 

direct hot-water heating. 

direct steam heating. 

electric heating..... 

exhaust steam heating. 

fans. 

forced hot-water circulation. 

furnace heating. 

heat loss from buildings. 

hot-water heaters.*. 

indirect hot-water heating. 

indirect steam heating. 

methods for various classes of buildings 

principles of ventilation. 

steam boilers. 

systems of warming. 

temperature regulators. 

vacuum systems. 

Heating and ventilation of 

apartment houses. 

churches.. 

greenhouses and conservatories........ 

halls. 

hospitals. 

office buildings. 

school buildings. 

theaters. 

Heavy-duty gears, design of. 1 . 

Heavy-service dumb-waiter. 

Heine boiler. 

Hero’s turbine. t . 

“Herringbone” spur-gear electric elevator. . 

High- and low-water alarms. 

High-pressure compressors. 

High-speed brake equipment. 

High-speed reducing valve. 

High steam pressures. 

High-tension magneto. 

Hilger gas-producer. 

Hindley gear. 

Hinged valves. 

Hob, details of.. 

Hoisting hook, proportions of. 

Holley carburetor. 

Hollow-plunger device. 

Horizontal fire-tube boilers. 

Horizontal machines. 

Horizontal water-tube boilers. 

Hornsby-Akroyd oil engine. 

Horsepower. 

Horsepower of boilers. 

Horsepower of pumps.' r . 

Horsepower for ventilation. 

Hot-tube ignition. 

Hot-water heaters. 

Howden system of forced draft. 


Vol. Page 

. VII, 11 

.VII, 11-223 

. VII, 204 

\ 11, 102, 126, 221 

. VII, 107 

. VII, 52 

. VII, 196 

. VII, 134 

. VII, 169 

. VII, 127 

. VII, 29 

. VII, 23 

. VII, 104 

. VII, 123 

. VII, 81 

. VII, 205 

. VII, 17 

. VII, 46 

. VII, 11 

. VII, 199 

. VII, 151 

. VII, 219 

. VII, 214 

. VII, 219 

. VII, 216 

. VII, 212 

. VII, 217 

. VII, 206 

. VII, 216 

. VI, 248 

. VI, 45 

. I, 121 

. IV, 361 

. VI, 228 

T 70 


III, 315 

III, 299 

III, 71 

IV, 219 

IV, 320 

VI, 69 

I, 397 

VI, 71 

VI, 234 

IV, 78 

VI, 168 

I, 84 

VI, 151 

I, 113 

IV, 164 

VI, 357 

I, 61, 344 
VI, 366 

VII, 52 

IV, 188 

VII, 104 

1 I, 243 




Note.—For page numbers see foot of pages. 


484 




























































INDIOX 


19 


Hub, keys, calculation of.. . . 

Hughes gas-producer. 

Humidostat. 

Hydraulic elevators. 

American improvements. 

direct-plunger types. 

early forms. 

high-pressure types. 

low-pressure types. 

power for. 

Hydraulic piping. 

Hydraulic plants. 

Hydraulic pumps, types used 

Hydraulic ram. 

Hydrogen. 


I 

Ice, storing and selling. 

Ice cans. 

Ice-making plants. 

can system. 

plate system... 

Ignition systems, gas engine. 

Ignitions and explosions in air compressors.. 

Impulse turbines. 

Inclined-grate stokers. 

Incrustation.. 

Independent brake operation. 

Indicated horsepower.. 

Indicated thrust. 

Indicator cards 

compressed-air. 

interpretation of. 

simultaneous. 

taking.. 

Indicator spring testing.. 

Indicators. 

Indirect-draft furnace. 

Indirect heaters, efficiency of. 

Indirect hot-water heating. 

Indirect steam heating.. 

Ingersoll-Rogler inlet and discharge valves.. 

Injection air supply. 

Injectors. 

Inside clearance. 

Inspection and testing of electrical machines 

electrical tests. 

mechanical tests. 

Instrument transformers. 

Insulation.. 

Insulation resistance. 

direct-deflection method. 

magneto-electric bell. 

voltmeter method. 

Integrating meter. 

Interchangeable brake system. 

Intercooler. 

Internal-combustion engines. 

classification. 

Note.—For page numbers see foot of pages. 


Vol. Page 

VI, 251 

IV, 319 

VII, 203 

VI, 93-174 

VI, 96 

VI, 156 

VI, 93 

VI, 140 

VI, 102 

VI, 364 

VI, 366 

VII, 397 

VI, 365 

I, 373 

VI, 52 


. V, 410 

. V, 371 

. V, 355 

. V, 356 

. V, 385 

. IV, 187 

. V, 118 

. IV, 413; VII, 398 

. 1,279,296 

. I, 324 

. Ill, 339 

II, 275; IV, 36 

. II, 99 

. V, 21, 33 

. II, 294 

II, 258 

. II, 263 

. II, 241 

II, 199, 231, 260, 307 

. VII, 31 

. VII, 84 

.VII, 15, 123 

.VII, 13, 81 

... V, 111 

.... IV, 183 

I, 71, 207; III, 150 

. Ill, 94 

. VII, 297 

.... VII, 300 

. VII, 297 

. . VII, 333 

... V, 427 

. ... VII, 314 

. VII, 314 

. . . VII, 316 

. . . VII, 315 

1, 312 

. Ill, 209 

" ". V, 96 

.IV, 12, 105 

.. IV, 105 


485 


























































20 


INDEX 


Internal-combustion engines (continued) Vol. Page 

Diesel oil engines. IV, 170 

low-pressure oil engines. IV, 163 

Otto-cycle engine. IV, 106 

Internally-fired boiler. I, 75 

Isothermal compression. V, 15 

Isothermal expansion. V, 144 

.1 

“ J ’ ’ electric compressor governor. Ill, 397 

Jacketing. II, 126 

Jet condenser. II, 139 

Jet pumps. I, 376 

Joints in boilers. I, 37 

Joy radial valve gear. II, 387 

Jump-spark ignition. IV, 208 


K 

Kent’s formula. I, 239 

Kerr turbine. IV, 453 

Kingston carbureter. IV, 80 

Knight sleeve-valve motor. IV, 146 

Knowles steam valve. I, 442 


L 

“L” head motor. 

“LN” passenger-car brake equipment... 

Lagging. .'.... . 

Lancashire boiler. 

Lap. 

Latent heat. 

Launch boilers. 

Layout of ice plant. 

Lead. 

Leather cups in valves. 

Leblanc condenser..-. 

Lenoir engine. 

Lentz boiler. 

Lever safety valve. 

Lever switches. 

Leverage. 

Lifting plates. 

Lifting straps. 

Lighting arrester. 

Limit devices. 

Limit stop in traction elevators. 

Limit valve. 

Liquid fuel data. 

Locomotive appliances. 

Locomotive boilers. 

ash pans. 

brick arches. 

capacity. 

care of. 

classification of. 

definition of. 

design of. 

diaphragm. 

draft. 

draft pipes. 

Note.—For page numbers see foot of pages. 


. IV, 141 

. Ill, 319 

.I, 233 

.I, 81; VII, 375 

. Ill, 216 

. V, 193 

. I, 155 

. V, 377 

II, 329, 332, 355; III, 93 

. IV, 345 

. II, 142 

. IV, 14 

. I, 103 

. I, 187 

. VII, 303 

. Ill, 307 

. VI, 328 

. VI, 327 

. VII, 427 

. VI, 167 

. VI, 223 

.VI, 120, 167 

. IV, 69 

. Ill, 148 

I, 99, 147; III, 48, 183, 190 

. Ill, 61 

. Ill, 63 

. Ill, 87 

. Ill, 183 

. III. 48 

. Ill, 48 

. Ill, 84 

. Ill, 64 

. Ill, 64 

. Ill, 64 




\ 


486 



























































INDEX 


21 


Locomotive boilers (continued) 

exhaust nozzle. 

explosion of. 

flues. 

grates. 

heating surface. 

high steam pressures.. 

netting. 

rate of combustion. 

smoke-box and front end arrangement 

spark losses. 

stack. 

stay bolts... 

steam or branch pipes. 

superheaters. 

Locomotive breakdowns. 

Locomotive driver brakes. 

Locomotive engines. 

boiler. 

care of. 

characteristics. 

connecting or main rods. 

crossheads and guides. 

cylinder and saddle. 

design of parts. 

frames. 

inside clearance.. 

lead.. .. 

mechanical efficiency. 

outside lap. 

piston and rods. 

running gear. 

side rods.. 

stokers. 

tender. 

trucks. 

types of.. .. 

valve friction. 

valve motion. 

valves. 

Locomotive frames. 

Locomotive operation. 

Locomotive rating. 

Locomotive stokers. . 

Locomotives troubles and remedies. 

boiler care. 

breakdowns.. 

distinctive features of locomotive... . 

drifting... 

emergencies. 

fuel waste. 

pounds. . 

steam waste. 

Locomotive truck brakes. 

Locomotive trucks. 

Loomis-Pettibone gas-producer. 

Loose-ring end-thrust blocks. 

Low-pressure hydraulic elevators. 

Low-pressure oil engines. 

Low-pressure turbines. 

Note.—For page numbers see foot of pages. 


Vol. 

Page 

. Ill, 63, 66 

. Ill, 

190 

. Ill, 

53 

. Ill, 

60 

. Ill, 

73 

. Ill, 

71 

. Ill, 

63 

. Ill, 

69 

. Ill, 

63 

. Ill, 

71 

. Ill, 

68 

. Ill, 

55 

■ HI, 

63 

. Ill, 

74 

. Ill, 

187 

III, 

312 

. Ill, 

93 

. II, 

71 

. Ill, 

198 

.. II, 

74 

HI, 

124 

.. HI, 

122 

III, 

120 

. . Ill, 

133 

. . Ill, 

117 

. . Ill, 

94 

. . Ill, 

93 


73 

. Ill, 

93 

. . HI, 

121 

. Ill, 

110 

HI, 

124 


130 


129 


125 


75 


108 


94 


105 



.. HI, 

145 


130 


.. Ill, 

183 


187 


179 

• HI, 

185 


174 


186 


180 


182 


312 


125 


IV, 308, 313 
VI, 77 
VI, 102 
IV, 163 
IV, 388 


487 





























































22 


INDEX 


Low-temperature compression system 

Low-tension magneto. 

Lubrication. 

of air cylinder. 

of locomotive. 

of pumps. 

of triple valve. 

Lubrication systems. 

Lubricator. 

Lugs or brackets. 


“M-18” brake valve.*. 

Mabbs elevator. 

Magnet control. 

Magnetos. 

Main reservoir. 

Mains and branches, sizes of. 

Make-and-break ignition. 

Management of dynamo-electric machinery.... 

electrical tests... ; . . 

erection. . ’. 

mechanical tests. 

operation. 

selection of machine. 

troubles, localization and remedy of. 

typical wiring connections. 

Manholes. 

Manning boiler. 

Marine boilers... 

cylindrical. 

rectangular.. 

water-tube.... 

Marine Diesel engines. 

Marine gas engines. 

Marine steam engines. 

bearings. 

comparison of marine with stationary types 

condensers. 

cranks. 

crosshead guides. 

cylinder. 

definition of terms. 

management of. 

methods of propulsion...’ ’ 

propellers, screw. 

propulsion. 

pumps. 

reversing mechanism. 

types of. 

Marsh gas. 

Marshall radial valve gear. 

Masonry. 

Mean effective pressures for air-expansion. .. 

Mechanical draft. 

Mechanical efficiency 

of air compressors. 

of engine. 

Mechanical indicator. ’ 

Note.—For -page numbers see foot of pages. 


Vol. 

Page 

.. V, 

269 

.. IV, 

206 

•• V, 

265 

.. Ill, 

229 

.. Ill, 

198 

I, 

467 

III, 

419 

. II, 

180 

. Ill, 

157 


72 


401 

VI, 

232 

VI, 

193 


199 

.111,214, 

239 

. VII, 

128 

IV, 

190 

VII, 225 

-364 

VII, 

300 

. VII 

226 

. VII, 

297 

. VII, 

293 

. VII, 

225 

. VII, 

334 

VII, 

240 

, 43, 72, 

169 

I, 

90 

; vii, 

376 

i, 

147 

i, 

145 

i, 

147 

IV, . 

174 

IV, 

159 

ii, 

84 

ii, 

92 

ii, 

90 

ii, 

96 

ii, 

91 

ii, 

91 

ii, 

90 

ii, 

84 

ii, 

103 

ii, 

85 

ii, 

100 

ii, 

98 

ii, 

96 

ii, 

94 

ii, 

85 

IV, 

52 

ii, 

386 

i, 

72 

V, 

146 

I, 

242 

V, 

117 

II, 

278 

VI, 

405 


488 




























































INDEX 


Mechanical power. 

Mechanical stokers. 

Metallic resistance, testing. 

drop, or fall of potential, method. 

Wheatstone bridge method. 

Meters. 

Meyer double-valve gear. 

Mietz and Weiss oil engine. 

Mietz and Weiss vaporizer. 

Miller valve. 

Mond gas-producer. 

Morgan gas-producer.... 

Mosher boiler. 

Motor-driven pumps. 

Motor-generator set. 

Motors, reversing direction of rotation 

Movable signals. 

Mufflers. 

Multiple distillers. 

Multiple-expaiision steam engines. 

Multitubular boilers. 


N 

Nagle valve. 

Nash carbureter. 

Nash vertical gas engine. 

Netting. 

Newcomen steam .engine. 

Niclausse boiler. 

Nitrogen.. .. 

Non-sectional boiler, definition of. 

Nordberg drop gear. 


O 

Oil buffer. 

Oil-cooled transformers. 

Oil gas. 

Oil separator or interceptor. 

Oil switches.... 

Oiling locomotive. 

Olefiant gas. 

“One-to-one” electric engine. 

Operating chain and ring.. .. 

Operating circuit safety devices. 

Operating-lever device... 

Operating problems in refrigeration. 

Operating troubles of pumps. 

Operating valve. 

Orsat flue gas analyzing apparatus. 

Otis Tufts valve. 

Otis valve. 

Otto cycle... 

Otto-cycle gas engines. 

Otto suction gas-producer. 

Outside lap. 

Overhead beams. 

Overhead floor. 

Overhead loading. 

Note.—For page numbers see foot of pages. 



23 

Vol. 

Page 

VII, 

325 

I, 277, 289 

VII, 

311 

VII, 

312 

VII, 

311 

II, 

307 

II, 

393 

IV, 

165 

IV, 

95 

VI, 

87 

IV, 

328 

IV, 

317 

I, 

122 

I, 

425 

IV, 

197 

VII, 

263 

III, 

159 

IV, 

254 

V, 

359 

II, 

124 

I, 

84, 89 


I, 

400 

IV, 

84 

IV, 

118 

III, 

63 

II, 

13 

I, 

126 

IV, 

52 

I, 

75 

II, 

409 


.VI, 225, 

414 

. VII, 

410 

• iv, 

64 

V, 

305 

VII, 305, 423 

. Ill, 

198 

• iv, 

52 

VI, 

226 

• VI, 

162 

• VI, 

409 

. VI, 

133 

V, 

465 

I, 

467 

VI, 

171 

I, 

308 

. VI, 

84 

. VI, 

87 


18 


125 

. IV, 

307 

. Ill, 

93 


290 


294 


297 


489 
























































24 


INDEX 


Vol. 

Overhead screen...\. 

Overhead valve motor. 

Oxygen. 


“PCpassenger brake equipment. HI, 

Pantograph... tvHaa 

Parsons turbine.. 1 v > *? DD > 

Partial filtration lubrication systems. II, 

Passenger elevator inclosures. VI, 

Paul vacuum heating system. VII, 

Pendulum governor. II, 

Performance data for gas engines. IV, 

fuel consumption.•■ • • •. IV, 

fuel consumption tests for commercial engines. IV, 

heat balances of four-cycle engines. IV, 

heat losses at various speeds and compressions. IV, 

Pielock superheater. Ill, 

Pilot valve.. • VI, 92, 

Pilot-wheel operation.• VI, 

Pintsch suction gas-producer. IV, 

Pipe connections.Ill, 422; VII, 99, 115, 125, 145, 

Pipe coverings. I, 

Pipe heaters, efficiency of. VII, 

Pipe fine....'... V, 

Pipe radiators. VII, 

Pipe sizes.VII, 70, 100, 120, 126, 

Pipes, expansion of.• ■ • • _ VII, 

Piping, systems of.VII, 59, 111, 

Piping of pumps. I, 

Piston. II, 

Piston displacement.. II, 

Piston lubricating device. VI, 

Piston packing. VI, 

Piston rings. II, 


Plant economy vs. boiler economy. 
Plates and joints, arrangement of.. 


Platforms.VI, 17, 


Plugs, fusible. 
Plunger. 


Pop safety valve. 
Poppet valves 
Porcupine boiler.. 


dy; vi, 

.. II, 

dOI 

417 

. . II, 199, 270 

I, 

301 

I, 

37 

.. VI, 

313 

.. VI, 

311 

.. VI, 

313 

. . VI, 

311 

, 96, 302, 

, 317 

VII, 

158 

I, 

174 

.. VI, 

157 

.. VI, 

166 

V, 

168 

V, 

180 

V, 

170 

I, 

189 

398; V, 

111 

I, 

142 

II, 

164 

.. V, 

61 

. VII, 

438 

... VII, 

440 


Note.—For page numbers see foot of pages. 


490 




























































INDEX 


Power-plant buildings (continued) 

power, methods of charging for. 

station arrangement. 

station records. 

Power-plant generators. 

Power requirements, elevator. 

belt-driven elevators. 

definition of power. 

electric elevators. 

hand operated elevators._. 

hydraulic elevators. 

Power stations. 

arrangement... 

buildings. 

electric plant. 

gas plant.. 

hydraulic plants. 

introduction. 

location of. 

records. 

steam engines. 

steam plant. 

steam turbines. 

substations. 

switchboards. 

Pownall system. 

Pressure apparatus. 

Pressure of boilers. 

Pressure gage. 

Pressure retaining valve. 

Pressures, volumes, and temperatures, relation of 

Prime movers.. 

Priming. 

Producer gas. 

Producer-gas plants. 

Prony brakes. 

Prosser expander. 

Pull machine. . 

Pulleys. 

Pulsometer. 

Pumps.. 

automatic control. 

capacity of. 

care. 

centrifugal. 

classification... 

‘ design and construction. 

erection of. 

* forcing. 

hydraulic ram. 

jet. 

lifting... 

lubrication. 

operating troubles. 

packing. 

piping. : . 

principles of action. 

reciprocating. 

rotary. 

setting of valves. 

Note.—For page numbers see foot of pages. 



25 

Vol. Page 

. VII, 

452 

. VII, 

444 

. VII 

445 

. VII, 

404 

• VI, 

357 

VI, 

358 

• VI, 

357 

. VI, 

374 

VI, 

357 

VI, 

364 

VII, 367- 

-452 

. VII, 

444 

. VII, 

438 

. VII, 

404 

. VII, 

402 

. VII, 

397 

. VII, 

367 

. VII, 

368 

. VII, 

445 

. VII, 

390 

. VII, 

374 

. VII, 

392 

. VII, 

434 

. VII, 

413 

. V, 398, 

403 

I, 

316 

I, 

66 

72; V, 

329 

III, 215. 

, 295 

• v, 

30 

• VI, 

57 

I, 

224 

..IV, 64, 

287 

iv, 

341 

8; VII, 

323 

I, 

57 

. . VI, 

114 

. . VI, 

49 


13 


130 

I, 

438 

.. VI, 

364 


466 


380 


a75 


401 

I, 

460 


371 


373 


376 


370 


467 


469 


467 


462 


367 

I, 

389 


378 


457 


491 































































26 


INDEX 


Pumps (continued) 

steam. 

steam valves. 

testing. 

troubles. 

types. 

valves... 

Push machine. 

Push-button control elevators 
Pyrometers. 


Vol. Page 

. II, 77 

. I, 440 

. I, 472 

. I, 469 

. I, 415 

I, 395, 401, 440, 468 

. VI, 117 

. VI, 198 

. I, 308 


Quadruple engine. 

Quick-action cylinder cap. 
Quick-action triple valve. 
Quick-action valve. 


R 

Racing-boat rating formulas. 

Rack guide. 

Radiation. 

loss of heat through. 

Radiators. 

cast-iron. 

connections. 

efficiency of. 

electric,. 

location of. 

pipe . 

types of. 

Rails, sanding of. 

Railway signaling. 

Rateau turbine. 

Rathbun gas engine. 

Rating of boilers. 

Raw water ice plants. 

can systems. 

plate systems. 

typical large plant. 

typical small plant. 

Reaction turbines. 

Real and Pichon compound turbine. 

Reamed holes. 

Reciprocating pumps. 

air chamber.. 

arrangement of parts...'. 

bucket. 

cylinder. 

design and construction. 

forcing. 

frames. 

lifting. 

packing. 

piston. 

plunger. 

ports. 

proportion of parts. 

pump ends.. 

stuffing box. 

types. .! !! ! ! 

Note.—For page numbers see foot of pages. 


II, 38 
III, 343 
III, 261 
III, 374 


. IV, 157 

. VI, 381 

.. .II, 120; V, 200 

. Ill, 89 

. VII, 34, 57, 110 

. VII, 53 

. VII, 65 

.VII, 57, 110 

. VII, 196 

. VII, 59 

. VII, 1 55 

. VII, 124 

. Ill, 428 

. Ill, 158 

. IV, 438 

. IV, 119 

. I, 63 i 

. V, 392 i 

. V, 394 

. V, 399 

. V, 403 

. V, 402 

IV, 476; VII, 398 

. IV, 363 

. I, 26 

. I, 205, 389 

. I, 404 

. I, 408 

I, 402 ! 

. I, 401 !! 

. I, 401 I 

. I, 391 j 

. I, 407 

. I, 389 ! 

. I, 403 

. I, 402 

. I, 404 

. I, 406 

. I, 409 

. I, 407 

. I, 406 

. I, 415 


492 

























































INDEX 


27 


Reciprocating pumps (continued) 

valves.... 

Rectangular marine boilers. 

Rectifier. 

Reducing valves. 

Reducing wheel.. 

Reduction gear. 

Re-evaporation. 

Refrigerants, tests of.. . . .. 

Refrigeration. 

Refrigeration, miscellaneous applications of 

breweries. 

chocolate making. 

cooling air in buildings. 

creameries. 

drying air for blast furnaces. 

oil refining. 

packing houses. 

precooling of fruit.. 

Refrigeration problems and solutions. 

absorption-plant. 

care of equipment. 

•classification of troubles. 

cold-air machine. 

compression plant. 

faulty design of plant. 

keeping organization together. 

raw water plants. 

steam plant. 

suggestions for different types of plants 
value of use of instruments and records 

Refrigeration systems. 

Registers.. 

Regulating fuel mixture. 

Return-air pumping system. 

Return duct. 

Return traps... 

Return-tubular boiler.. 

Return-tubular fire-box boiler. 

Reverse-plunger types. 

Reversing cock, action of. 

Reynolds-Corliss gear. 

Ribbed cylinder head. 

Riedler-Stumpf turbine. 

Rites inertia governor... 

Riveted joints in boilers. 

Rivets. 

Rock drill. 

Roller bearings, antifriction. 

Root boiler. 

Rope-driven compressors. 

Rope driving—....... 

Rotary pneumatic drills. 

Rotary pumps. 

Running gear. 

Rust boiler. 


S 

“S” air-compressor governor. 

“SD” air-compressor governor. 

Note ,— for page numbers see foot of pages. 


Vol. Page 

. I, 395, 401 

. I, 145 

. V, 231 

I, 194; III, 379 

. II, 253 

. VI, 217 

. II, 121 

. V, 215 

. V, 183-479 

. V, 454 

. V, 462 

. V, 461 

. V, 457 

. V, 458 

. V, 462 

. V, 456 

. V, 461 

. V, 465 

. V, 472 

. V, 466 

. V, 465 

. V, 477 

. V, 475 

. V, 469 

. V, 466 

. V, 479 

. V, 477 

. V. 472 

. V, 465 

. V, 218 

. VII, 97 

. IV, 253 

. V, ' 176 

. VII, 39 

1,229; VII, 142 

. I, 92 

. I, 104 

. VI, 149 

. Ill, 315 

. II, 406 

. VI, 349 

IV, 424, 428, 469 

. II, 169 

. I, 25 

. I, 27 

. V, 151 

. VI, 19 

. I, 116 

. V, 46, 63 

. VII, 235 

. V, 168 

. I, 378 

. Ill, no 

. I, 135 


III, 235 
III, 237 


493 



























































28 


INDEX 


“SF” air-compressor governor. 

“SME” electric-car brake equipment. 

“SM-1” and “SM-3” electric-car brake equipment 

“S-6” independent brake valve. 

Sabathe atomizer. 

Safety, factors of. 

Safety devices... 

cable safeties. 

car safeties.. 

car signals.. 

center line. 

conclusion.. 

cushioning devices.'. 

electric elevator control. 

inclosures. 

safeguards necessary. 

slack-cable stop. 

Safety dogs..*. 

Safety valve. 

Sand blast. 

Saturated vapor... 

Savery steam engine.,. 

Scale, effect of. 

Scale formation. 

Scales.. 

Scavenging. 

Schebler carbureter. 

Schenectady or Cole superheater. 

Schmidt superheater. 

Sectional boilers. 

Sections of boiler...•. 

Selection of electrical machine. 

attention. 

capacity. 

construction. 

cost. 

finish. 

form. 

handling. 

regulation.. 

simplicity. 

Sellers injector. 

Semi-automatic shaft gate. 

Separately-fired superheater. 

Separating calorimeter. 

Shaft cushinoing. 

Shaft diameter, determination of. 

Shaft gate, semi-automatic.. 

Shaft governor. 

Shaft inclosures. 

Shaft size, determination of. 

Shafting. 

Shapley boiler. 

Sheave members, proportions of. 

Sheave pulley.‘. 

Sheet-steel guards. 

Shock absorbers. 

Shop equipment. 

Shrinkage strains in sheaves. 

Note.—For page numbers see foot of pages. 


Vol. 

Page 

.... Ill, 

239 

. . . Ill, 384 

, 386 

.... HI, 

384 

.... Ill, 

252 

.... IV, 

101 

.. . . VI, 

234 

. . . . VI, 60, 

, 380 

. . . . VI, 

389 

. .. . VI, 

380 

. .. . VI, 

403 

.... VI, 

60 

.... VI, 

415 

. .. . VI, 

413 

.... VI, 

408 

.... VI, 

392 

.... VI, 

380 

.... VI, 

60 

.... VI, 

30 

. . . . I, 72, 

187 

.... V, 

170 

.... II, 

278 

.... II, 

11 

.... Ill, 

89 

.... I, 

324 

.... II, 

307 

... . IV, 

107 

.... IV, 

75 

.... Ill, 

77 

.... Ill, 

77 

.... VII, 

49 

.... I, 

67 

.... VII, 

225 

.... VII, 

225 

.... VII, 

226 

.... VII, 

225 

VII, 

226 

.... VII, 

225 

.... VII, 

226 

.... VII, 

226 

.... VII, 

226 

.... VII, 

225 

.... Ill, 

150 

.... VI, 

395 

.... II, 

131 

.... I, 

351 

.... VI, 

413 

.... VI, 

237 

.... VI, 

395 

. ... II, 

166 

VI, 

392 

. . . .VI, 239 

, 240 

.... VII, 

237 

I, 

105 

.... VI, 

256 

.... VI, 

255 

.... VI, 

321 

. . VI, 

147 

. . . . I, 

25 

.... VI, 

256 


494 





























































INDEX 


29 


Shrouded gears, use of. . 

Shunt-wound motors. 

Side braces used with stiles. 

Side rails of platform. 

Side rods. 

Sidewalk electric lift. 

Signal valve. 

Signaling device. 

Simple engines. 

Single-belt electric elevators... 

Single-ended boiler. 

Single-flue boiler.. 

Single gear. 

Single pumps. 

Single-stage air compressors. 

Single-stage compressor. . 

Single-stage impulse turbines. 

Single-tube boiler. 

Siphon relief. 

Skimmers. 

Slack-cable stop. 

Sling type of hand-power elevator. 

Slip. 

Smith spun-glass tar extractor and gas cleaner 

Smith thermostatic regulator. 

Smoke indicators and recorders. 

Smoke prevention. 

Snow oil engine. 

Solenoid brake. 

Soot blowers. 

Spark losses. 

Spark plugs. 

Specific heat. 

Speed counter.. 

Speed regulator, introduction of. 

Speeds, variable. 

Spray filter. 

Spring buffer. 

Spur-gear steam elevator. 

Spur-geared machines. 

Spur gears, duplex arrangement of. 

Spur teeth, proportions of. 

Stacks.... 

Stacks, size of.. 

Stacks and casings... 

Standard marine boiler. 

Starting locomotive. 

Stationary boilers. 

Stationary return-tubular boiler. 

Stay bolts. 

Stay rods. 

Stays... 

Steam, action of. 

Steam, properties of. 

Steam and auxiliaries. 

Steam blowers. 

Steam boilers. 

sectional. 

tubular. 

Note .— For page numbers see foot of pages. 


Vol. Page 
. . VI, 248 

. . VII, 257 

. . VI, 323 

. . VI, 313 

. . Ill, 124 

. . VI, 231 

. . Ill, 379 

. . VI, 403 

. . II, 36, 357 
. VI, 231, 362 
I, 93, 95, 147 
I, 84, 93 
. . VI, 214 


I, 

415 

III, 

218 

V, 

55 

IV, 

413 

I, 

88 

VI, 

111 

I, 

217 

. VI, 60, 

, 391 

. VI, 

11 

II, 

102 

• IV, 

339 

- iv; 

335 

i, 

311 

i, 

335 

• IV 

173 

• VI, 

410 

I, 

230 

. Ill, 

71 

• IV, 

222 

• V, 

191 

; vii, 

321 

VI, 

153 

. VI, 

179 

. VII, 

205 

• VI, 

414 

• VI, 

84 

• VI, 

48 

VI, 

248 

• vi, 

249 

. iii, 

68 

. VII, 

124 

• VII, 

87 

I, 

150 

. Ill, 

200 

I, 

104 

I, 

97 

III, 

55 

I, 

45 


44 


45 


278 


220 


289 

. vii; 

46 


49 


46 


495 





























































30 


INDEX 


Steam chest.<.. 

Steam compressor governors. 

Steam condensation. . 

Steam dome. 

Steam-driven compressors. 

Steam elevators. 

Steam engine.. 

classification. 

compound. 

condensers.. 

cost of engines and operation. 

crank effort. 

early history. 

erection and operation. 

farm or traction. 

flywheel. 

governor. 

locomotive. . 

marine.. .. 

mechanical and thermal efficiency. 

operation economies. 

parts of. 

selection of. 

simple. 

special types. 

specifications. 

stationary. 

superheating. 

tests. 

troubles and remedies. 

water pumps. 

Steam-engine indicators. 

assembling and adjusting of. 

indicator spring testing. 

interpretation of indicator cards. 

physical theory. 

properties of steam. 

taking cards. 

testing. 

troubles and remedies. 

types.. 

Steam-engine losses, analysis of. 

clearance. 

cooling by expansion. 

exhaust waste. 

friction. 

radiation. 

steam condensation and re-evaporation 

Steam-engine operation. 

adjusting eccentric strap. 

adjustment of connecting-rod box. 

care of bearing caps. 

competent engineer a requisite. 

governor. 

lining up crosshead. 

lubrication. 

starting. 

valve setting. 

Steam engines. 

Note.—For page numbers see foot of pages. 


Vol. 

Page 

II, 

29 

. Ill, 

234 

11, 

121 

I, 

225 

V, 

56 

. VI, 81-92 

II, 11 

-228 

II, 

35 

II, 

36 

II, 

135 

II, 

190 

II, 

151 

II, 

11 

II, 

170 

II, 

60 

II, 

152 

II, 

158 

II, 

71 

. II, 

84 

II, 

117 

II, 

123 

II, 

17 

II, 

40 

II, 

36 

II, 

83 

II, 

185 

II, 

41 

II, 

128 

. II, 193, 

305 

II, 

220 

II, 

77 

. II, 231 

-319 

II, 

260 

II, 

241 

II, 

294 

II, 

271 

II, 

278 

II, 

263 

II, 

305 

II, 

314 

II, 

232 

II, 

120 

II, 

123 

II, 

121 

. II, 

122 

II, 

123 

II, 

120 

II, 

121 

11, 

173 

II, 

174 

II, 

174 

II, 

173 

II, 

173 

II, 

175 

II, 

174 

II, 

175 

11, 

182 

II, 

175 

vii, 

390 


496 





























































INDEX 


31 


Steam engines with steam elevators... 

Steam-flow meters. 

Steam gages. 

Steam jets... 

Steam piping. 

arrangements. 

expansion. 

fittings. 

lagging. 

location.'. 

loss in pressure. 

material. 

mounting. 

size. 

Steam plant. 

boilers.. 

steam engines. 

Steam port. 

Steam separators... 

Steam space of boilers. 

Steam supply, regulating. 

Steam traps. 

Steam tables. 

Steam turbines. 

advantages. 

commercial. 

compounding. 

fundamental principles. 

governing. 

history... 

installation. 

low-pressure. 

' nozzles. 

performance. 

starting.. .. 

tests... 

troubles and remedies... 

types of. 

Steam valves. 

Steam waste in a locomotive. 

Steel... 

Steel-beam tables, use of. 

Steel-plug end-thrust blocks 

Steel plunger... 

Stephenson link motion. 

Stephenson valve gear. 

Stiles. 

Stirling boiler. 

Stokers, locomotive. 

Stokers, mechanical. 

Stoking. 

Stop buttons. 

Storage air-brake equipment. 

Storage batteries. 

Storing and selling ice.... 

Straight air-brake system. 

Straight-line compressors. 

Strainers.. 

Street mechanical stoker. 

Note.—For page numbers see foot of pages. 


Vol. Page 

. VI, 90 

. I, 315 

.1, 176; III, 154 

. I, 244 

. .1, 72, 196; VII, 379 

.. VII, 380 

. VII, 383 

. VII, 383 

. VII, 384 

. VII, 384 

. VII, 383 

. VII, 381 

. VII, 383 

. VII, 383 

. VII, 374 

. VII, 374 

. VII, 390 

II, 351 

. I, 224 

. I, 64 

.Ill, 171, 193 

. I, 227 

... II, 201, 280 
IV, 357-500; VII, 392 

. IV, 359; VII, 392 

. IV, 413 

IV, 376 

. IV, 368 

.... IV, 491 

.. IV, 361 

. IV, 397 

. IV, 388 

.... IV, 375 

. IV, 401 

.... IV, 495 

. IV, 406 

.... IV, 496 

. IV, 378; VII, 393 

. I, 440 

. Ill, 182 

. I, 13 

VI, 300 

. VI, 76 

. . VI, 158 

II, 373 

III, 95 

VI, 321 

I, 133 
. . Ill, 130 

... I, 164, 277 

VII, 390 

. VI, 119 

. . Ill, 409 

. . . VII, 412 

. . . V, 410 

. Ill, 384 

.... V, 55, 74 
. I, 220, 463 

III, 132 


497 





























































32 


INDEX 


Vol. Page 

Stresses, action of. VI, 233 

Stromberg carbureter. IV, 82 

Stuffing box. V, 262 

Stuffing box and packing. II, 24 

Sturtevant fuel economizer. I, 248 

Sturtevant turbine. IV, 432 

Submerged condenser. V, 290 

Substations. VII, 434 

Sulzer gear. II, 412 

Superheated steam.II, 284; VII, 384 

Superheaters.I, 220; III, 74 

Superheating. II, 128 

Surface condenser. II, 137 

Switchboards. VII, 413 

oil switches. VII, 423 

panels. VII, 415 

direct-current feeder. VII, 421 

direct-current generator. . VII, 417 

exciter. VII, 422 

synchronous converter.:. VII, 420 

three-phase feeder. VII, 421 

three-phase induction-motor. VII, 420 

total output. VII, 422 

safety devices. VII, 427 

Switches.‘ ‘ VIl’ 303 

lever. VII, 303 

_ oil. VII, 305 

Synchronous converters. VII, 247 

comparison with d.c. generator. VIl’ 247 

switching of. VPl’ 251 

us f. VII, 247 

voltage relations in. YU 247 

Syracuse gas-producer..IV, 299, 314 


Tables 


T 


air, number of changes in, required in various rooms. 

air, power required for moving under different pressures. 

air, quantity of, required per person. 

air chamber, dimensions of. 

air-compression, losses in, due to heat of compression. 

air flow through flues of various heights under varying conditions 

of temperature. 

air-lift pumps, constants for. . " ’ 

air-lift pumps, well pipe sizes for. ’ ” ’ \ 

air required for ventilation of various classes of buildings. ..... 

allowable piston speeds for various engines. 

altitude and atmosphere pressure, relation between. 

ammonia, solubility of, in water. 

aqua ammonia, strength of. 

Arctic refrigerating machine, general dimensions of. 

average maximum efficiencies of generators. 

average mean effective pressures with various fueis..] [ ’ ’ 

average mechanical efficiency of various engines. 

axle mounting, hydraulic pressures used in. 

ball valves, spring wire sizes for. 

bare pipe data.’ 

barometer readings. 

bends for various pipe diameters. 


Note.—For page numbers see foot of pages. 


VII, 

VII, 

VII, 

V 

V, 


VII, 

I, 

I, 

VII, 

IV, 

V, 

l 

Vll’ 

IV, 

IV, 

III, 

I, 

I 


21 

180 

20 

405 

21 


96 

434 

435 
20 

262 

38 

214 

216 

379 

406 

260 

265 

116 

400 

234 

368 

367 


498 

























































IN DUX 


33 


Tables (continued) Vol. Page 

bituminous coal and low-grade fuel data. IV, 348 

boiler, size of, for different conditions. VII, 48 

boiler efficiencies.VII, 378, 385 

boiler floor space. VII, 377 

boiling point and latent heat of substances. V, 207 

Buckeye engine test, indicator diagram data for.II, 216-219 

calcium brine solution, properties of. V, 321 

can ice plants, space required for. V, 377 

capacity of compressor and efficiency of compression, effect of 

various temperatures on. V, 27 

capacity ratios of converters. VII, 437 

changing lap, travel, and angular advance, effect of. II, 350 

clearance, per cent of. IV, 259 

coals, analyses and heat value. I, 338 

cold storage, duration and temperature of. V, 451 

cold storage rates. V, 452 

cold storage temperatures and rates. V, 424 

combustion products. IV, 54 

compound pump data. I, 457 

comparative dimensions of Stephenson and Walschaert gears... Ill, 104 

comparative heat losses in large gas and Diesel engines. IV, 259 

compressed-air table for pumping plants. V, 172 

compression pressures, values of. IV, 32 

constants of indicator springs.... II, 239 

copper wires, safe-carrying capacities of. VII, 302 

cost of installation and operation of steam plant for one year... II, 192 

crank-pin mounting, hydraulic pressure used in. Ill, 117 

crank-pins, working stress for. HI, 139 

critical data. : . V, 206 

cubic feet of gas to be pumped per ton of refrigeration. V, 259 

diagram factors for explosion engines. IV, 261 

Diesel motor ships of 1913, dimensions of. IV, 178 

direct radiating surface supplied by mains of different sizes and 

lengths of run. VII, 121 

disc fans, capacity, speed, etc. • VII, 185 

discharge through orifice 1 inch in diameter at 100 pounds 

pressure. II, 1*" 

double-riveted joints, efficiencies of. I, 34 

down-draft producer gas. IV, 35^ 

dry-air, weights and volumes of. V, 1’ 

dry pipe sizes. IH, 15 

effect of clearance. 

effects of temperature on action of steam. |V, ^92 

efficiency curves of engines. yy 

efficiency obtained by use of condenser. 

engine costs. Vv yfi 

estimated costs of making ice. y 

evaporation, factors of. v ™ 

exciter data.. ■••••. v T V 71 

explosive air-gas mixtures, limits of proportion lor. .......... . iv, /1 

explosive air-gas mixtures at different temperatures, limits ot 

proportion for. . 1 y 

fan speeds, pressures, and velocities of air-fiow. vii, o 

fans, effective area of. HI* 136 

fiber stresses. . yjy 37 

firepot dimension... t’ 400 

fire pumps, dimensions and capacities ot. y 

flexible valve data. ’ 

Note.—For page numbers see foot of pages. 


499 























































INDEX 


34 


Tables (continued) 

flow of steam in pipes of other lengths than 100 feet, factors for 

calculating... 

flow of steam in pipes under initial pressure above 5 pounds, 

factors for calculating... 

flow of steam in pipes of various sizes. 

forged-steel billets..... 

friction of water in pipes... 

fuel consumption of internal-combustion engines. 

fuel gases, volumetric composition of.•. 

full-load ratios for converters.. 

fusion and vaporization data of substances... 

gas yield of coals of different calorific values. 

gases, evaporative power of...' 

gasoline and kerosene, fractional distillates for. 

globe valves, tees, and elbows, effect on pressure in pipe line. . . 
grate area per h.p. for different rates of evaporation and com¬ 
bustion . 

. heat balances of gas and oil engines. 

heat cost of various priced fuels. 

heat generated by absorbing ammonia. 

heat loss, factors for calculating for other than southern exposures 
heat losses in B.t.u. per sq. ft. of surface per hour, southern 

exposure... 

heat losses at various speeds. 

heaters, dimensions of. 

heating surface, ratio of to grate area.... 

heating surface supplied by pipes of various sizes. 

heating systems, relative cost of. 

heights of governor for different speeds of engine.g 

hinged valve data.. 

horsepower developed per cu. ft. of air in compressing from 
atmospheric pressure to various gage pressures...... 

horsepower per cu. ft. of water for different heads. 

horsepower required to compress 100 cu. ft. of air from atmos¬ 
pheric to various pressures. 

horsepower transmitted by cold-rolled shafting at various speeds. 

hydraulic ram data. 

ice plants of varying capacities, costs in. 

indirect radiating surface supplied by pipes of various sizes. 

influence of height above sea level on volumetric efficiency. 

isothermal and adiabatic pressures in air-compression, multi¬ 
pliers for determining. 

lap-welded boiler tubes, dimensions of. 

lift and inlet head of various temperatures of water. 

liquid fuels. 

locomotives, classification of. 

locomotives, comparison of English and American. 

loss of pressure in pipes due to friction. 

mains, sizes of, for different conditions. 

maximum capacities of pumps for boiler feeding. 

moisture, ash, and fuel consumption for low-grade fuels. 

nonconducting power of substances. 

oval pipe dimensions. 

petroleum products and water, relative density of... ’ ’ ’ 

pipe heater data. 

pipe sizes. 

pipe sizes, suction and delivery.. ' ’ 

pipe sizes from boiler to main header.. 

pipe sizes for radiator connections. 

Note.—For page numbers see foot of pages. 


Vol. Page 
VII, 


VII, 

VII, 

III, 
I, 

IV, 
IV, 

VII, 

V, 

IV, 

I, 

IV, 


71 

116 

466 

271 

63 

437 

196 

349 

342 

73 


V, 

130 

VII, 

47 

IV, 

272 

IV, 

258 

V, 

240 

VII, 

25 

VII, 

24 

IV, 

270 

VII, 

165 

III, 

74 

VII, 

74 

VII, 

14 

II, 

163 

I, 

39? 

V, 

VII, 

37 

402 

V, 

40 

VII, 

236 

I, 

375 

V, 

412 

VII, 

101 

IV, 

263 

V, 

130 

I, 

56 

I, 

370 

IV, 

69 

III, 

21 

III, 

20 

V, 

129 

VII, 

131 

I, 

419 

IV, 

351 

V, 

430 

VII, 

42 

IV, 

68 

VII, 

164 

VII, 

169 

I, 

464 

VII, 

77 

VII, 

76 


500 


















































INDEX 


35 


Vol. Page 

I, 

403 

VII, 

374 

IV, 

346 

IV, 

55 

. . 11, 282, 

283 

I, 

410 

r- 

. VII, 

121 

ct 


. . VII, 

126 

VII, 

75 

I, 

235 

. VII, 

57 

V, 

209 

v, 

208 

.. VII, 

43 

.IV, 266, 

267 


Tables (continued) 

piston rods, sizes of... .. .. 

power station equipment, original and extensions. VII, 

producer-gas power plant data. 

properties of gases. IV, 

properties of saturated steam.H> 282, 

pumps, capacity of.. • • • 

radiating surface on different floors supplied by pipes of differ¬ 
ent sizes . 

radiating surface supplied by pipes of various sizes, indirect 

hot-water system. 

radiating surface supplied by steam risers... VII, 

radiation of heat, relative value of preventive. I, 

radiators, coils, etc., efficiency of. VII, 

refrigerants, comparative values of three. V, 

refrigerants, qualities of principal. V, 

registers, sizes of, for different sizes of pipe.• VA b 

relative flywheel weights. . * 

required thickness of cylinder walls to resist maximum explosion 

pressure. 

return, blow-off, and feed pipes, sizes for. 

riveted hydraulic pipe data. 

riveted lap joints, proportions of. 

rivets, dimensions of. 

safe loads uniformly distributed for standard and special 

* channels. 

safe loads for wood beams. v b 

salt brine solution. ’ 

saturated ammonia, properties of.. X 

saturated carbon dioxide, properties of. v, 

saturated steam, properties of... ..•. b ^ 

saturated sulphur dioxide, properties of....... . 

schedule for location of gasoline motor troubles. J-JL> 

shrinkage allowance. 

slip, allowance for.. 

specific heat of food products..... 

specific heat and specific gravity of beer wort. v, 

specific heat of various substances under pressure. . TT y 

spoke data, foundry rule. 

spoke data, general. T 

stack sizes by Kent’s formula. VI J> 

standard cable data.•. 

standard lap and clearance valves. 

standard wire data. ••••••••:■•••' j. 

stay bolts with V-threads, allowable loads. 

stays and stay bolts, maximum allowable stress. ^ 

steam consumption tests. 

steam pipes, sizes of returns for.... yTT 

steam table with and without condenser. j’ 

steel, chemical composition of. jij’ g 2 ^ gg 

superheater tests......... • . y’ 203 

temperature reduction of various mixtures. > 

temperatures due to adiabatic compression. > 

temperatures used in brewing processes. • • • .. jy’ 

test results and total plant efficiency of producers.. jv, 

theoretical thermal efficiency, effect of specific heats on. IV, 

thermometer scales.. \ 

triplex single-acting power pumps, data lor. jy’ 

typical producer-gas analysis. 

Note.—For page numbers see foot of pages. 


IV, 

269 

VII 

78 

VII, 

400 

I, 

32 

I, 

28 

VI, 

356 

VI, 

316 

VI, 

312 

V, 

322 

V, 

213 

V, 

212 

I, 348, 349 

V, 

212 

IV, 

274 

III, 

111 

I, 

411 

V, 

447 

V, 

195 

V, 

194 

III, 

112 

111 , 

111 

I, 

241 

VII 

416 

II, 

414 

VII, 

416 

I, 

51, 52 

I, 

51 

. IV, 

408 

. VII, 

76 

. VII, 

392 

I, 

13 

. Ill, 

82, 83 

V, 

203 

V, 

20 

v, 

455 

. IV, 

351 

. IV, 

34 

V, 

192 

I, 

422 

. IV, 

288 


501 

























































36 INDEX 

Tables (continued) Vol. Page 

up-draft pressure producer gas. IV, 350 

U. S. government test of steam and producer plants. IV, 342 

usual compression pressures. IV, 259 

valve tests. Ill, 109 

variation of injection air pressures with varying loads. IV, 101 

volumes, pressures and temperatures, relation of..... V, 31 

volumetric efficiencies and horsepower required in air compres¬ 
sion at Various altitudes, relation of. V, 41 

wall thickness for power plants. VII, 440 

warm-air pipe dimensions. VII, 40 

water flow data. VII, 387 

water flow through pipes. VI, 368 

water pressure data. VII, 399 

water pressure under different heads. I, 374 

weight of reciprocating parts of various engines. IV, 268 

Westinghouse air compressors, data for. Ill, 219 

working capacity of 19-wire strand iron hoisting cables. VI, 272 

wort cooling. V, 455 

yield of producer gas per pound of fuel. IV, 351 

Tabor indicator. II, 236 

Tachometers.II, 200; VII, 322 

Tandem-compound engine. II, 38 

Tandem gear. VI, 214 

Tandem worm and gear. VI, 78 

Tapered cylinder head. VI, 349 

Telescopic guide. VI, 162 

Telethermometer. VII, 203 

Temperature regulators. VII, 199 

air-compressor. VII, 199 

damper. VII, 202 

diaphragm motor. VII, 202 

diaphragm valve. VII, 201 

humidostat. VII, 203 

telethermometer. VII, 203 

Tender. Ill, 129 

Terry turbine.IV, 429, 470 

Testing boiler steel, rules for. I, 18 

Testing machines. I, 17 

Testing pumps. I, 472 

Thermal efficiency. II, 293 

Thermodynamics of internal-combustion cycle. IV, 18 

Thermometers.~.I, 308; II, 198, 273, 307 

Thermostat. VII, 200 

Thompson automatic valve gear. II, 401 

Thornycroft-Marshall boiler. I, 125 

Thread angle. VI, 66 

Throttle valve. HI, 154 

Throttling calorimeter. i’ 352 

Through-tube boilers. I, 99 147 

Thrust-machine piston rod. Vi, * 353 

Time tables. Hi’ i7g 

Timers. ! IV,’ 206 

Timing valve. IV 189 

Tools. i’ 72 

Toothed gearing. VII* 236 

Torque... .. VIl| 323 

1 ower scrubbers. IV 337 

Track channelers. V 160 

Traction elevators. yjj 221 

Note.—For page numbers see foot of pages. 


502 



























































INDEX 


Traps. 



37 

Vol. 

Page 

II, 

60 

VI, 

243 

III, 

143 

III, 

411 

III, 

144 

III, 

176 

III, 

160 

VII, 

408 

V, 

127 

VI, 

209 

VI, 

360 

VI, 

163 

I, 

227 

I, 279, 272 

VI, 

165 

II, 

38 


Triple valves. 

Triplex pumps. 

.ill, Z1U, ^JLO, ZDV, 

. V, 

4:10 

421 

383 

1 .. 

. V. 

275 

lUUmpillciugciai.mg, . . . . . . , 

Troubles of dynamo-electric machinery, localization and remedy oi. V11, 

dynamo fails to generate. VII, 

heating of armature. ^11, 

heating of bearings. Xii* 

heating of commutator and brushes. vtt 

heating of field magnets. ^11, 

334 

360 

345 

348 

344 

347 

356' 

I11AJUU1 OlUpo Ui itino .. 

. VII, 

351 


. VII, 

336 

sparKing at cuiiiiiitibctLui. 

. VII, 

354 


. VII, 

363 

voltage or geneiatui nut . 

Troubles and remedies 

. II, 

314 


.. II, 

220 

steam .. 

.. II, 

415 


. VI, 

325 

l russ Deam, use oi. 

. I, 

182 



323 


. I, 52, 

161 



46 



425 

1 urbme-ariven pumps.. 

. I, 

326 



398 



108 



224 

Two-stage air compressors. 

::. vi, 

97 

Two-way operating valve. 

. I, 71 

-166 




w 

. v, 

164 

Undercutting track channelers. 

. I, 283 

, 299 



51 



188 

Units of heat measurement. .. 


195 

Unity of capacity, refrigerating piam . 

. v, 

67 

V 

. hi, 

209 

311 

151 

Vacuum cooling tower. . . 


Vacuum system of heating. 

Note ,— For page numbers see foot of pages. 




503 
























































38 


INDEX 


Vacuum system of heating (continued) 
Paul system. 


Vol. Page 


analytical summary 


globe. 


Venturi meter. 

Vertical fire-tube boilers... 
Vertical water-tube boilers. 


V-notch meter. 


Wagon boiler. 


W 


. VII, 

155 

. VII, 

151 

. V, 304, 

365 

II, 

321 

II, 

337 

. Ill, 

108 

IV, 

239 

. 11, 321- 

-424 

II, 

331 

II, 

412 

. II, 393, 

419 

II, 

405 

II, 

322 

II, 

321 

II, 

384 

II, 

398 

II, 

373 

II, 

351 

II, 

415 

II, 

337 

II, 

323 

II, 

361 

. Ill, 

94 

• iv, 

240 

VII, 68, 

119 

VII, 68, 

119 

VII, 

68 

. VII, 

138 

. VII, 

119 

VII, 

68 

. VII, 

136 

. VII, 

70 

III, 

240 

IV, 

87 

VII, 

93 

. VII, 

17 

. VII 

22 

. VII, 

19 

VII, 

17 

. VII, 

18 

. VII, 

17 

VII, 

17 

. VII, 

17 

. VII, 

21 

VII, 

21 

I, 

313 

I, 

88 

I, 

130 

. IV, 

212 

V, 

391 

V, 

384 

IV, 

262 

V, 

42 

I, 

313 

• V, 

265 

I, 

76 

• VI, 

34 


Note.—For page numbers see foot of pages. 


504 


























































INDEX 


39 




Walschaert radial valve gear. 

Walschaert valve gear. 

Warm-air flues..,.. 

Warm-air pipes... 

Warren tandem gas engine. 

Water column, pressure of.. 

Water columns. 

Water consumption. 

Water-cooled transformers.. 

Water cooling, gas engines. 

Water economy... 

Water-end auxiliaries. 

Water evaporation per pound of fuel. 

Water-flow rate, computation of. 

Water gages. 

Water gas. 

Water grates. 

Water jackets. . 

Water-leg construction. . 

Water-seal motor.. 

Water separator for air pipe lines. 

Water table.. 

Water-tube boilers.I, 75, 109, 

advantages.. 

circulation in. 

horizontal....... 

Water-tube marine boilers. 

Water turbines. 

Watt indicator... 

Watt steam engine. 

Webster vacuum heating system. 

Weights, counterpoise. 

Welded joints... 

Westinghouse air-brake system... 

Westinghouse electric-car air-brake systems. 

Westinghouse gas engine.. 

Westinghouse gas-producer .. 

Westinghouse impulse turbine....... 

Westinghouse plain automatic air brake. 

Westinghouse straight air brake. 

Wet- and dry-bottom boilers. 

Wet-plate system. 

Wheels. 

Whistle. 

% Whistle signals. 

Whittier limit valve. 

Wickes boiler. 

Wilkinson turbine.. 

Wilson compound turbine. 

Wire cables. ; . 

Wire ropes introduced in elevator. 

Wiring. 

concealed. 

exposed.. ...•;••••.: ■ .. 

safe-carrying capacities of copper wires. 

size of conductors.. 

Wood beams, safe loads for. 

Wood guards. 

Wootten boiler. 


Vol. 

Page 

... II, 

387 

.. Ill, 

99 

... VII, 

91 

... VII, 

40 

... IV, 

130 

... VI, 

369 

... I, 

179 

... VI, 

371 

... VII, 

411 

... IV 

249 

... VI, 

151 

... I, 

200 

... I, 

63 

... VI, 

367 

71, III, 

154 

... IV, 

62 

... Ill, 

61 

.-. . V, 91 

, 263 

. . . 1 , 

38 

. . . VII, 

152 

... V, 

139 


147 


56, 261; VII, 49, 376 

. I, 110 

. I, 156 

. I, 113 

. I, 147 


.... VII, 

398 

. . . . II, 

232 

. . . . II, 

15 

.... VII, 

151 

... . VI, 

331 

.... I, 

36 

. . . .Ill, 214-383 

.... Ill, 

384 

. . . IV, 115, 

135 

.. . . IV, 

311 

.... IV, 

435 

.... HI, 

208 

.... HI, 

208 

I, 

146 

.. . . V, 

385 


110 


154 


158 


123 


130 


451 


364 


270 


23 

VII, 

300 


300 


300 


302 

.... vn; 

301 


312 


320 


103 


ffoteFor page numbers see foot of pages. 


505 
































































40 


INDEX 


Vol. Page 

Working pressure in hydraulic elevators. VI, 364 

Worm-gear steam elevator. VI, 81 

Worm-geared machines. VI, 53 

Worm gears, proportions of. VI, 249 

Worm-shaft speed and pressure. VI, 57 

Worm- and spur-gear combinations. VI, 248 

Worm and wheel. VI, 214 

Worthington boiler. I, 119 

Wrought iron. I, 12 

Y 

York refrigerating machine. V, 279 

Z ' 

Zeuner diagram. II, 337 

Zoelly turbine. IV, 442 

Note.—For page numbers see foot of pages. 


3!;7T-2 


506 


























































































































































